The Farlex Grammar Book > English Spelling and Pronunciation > Spelling Conventions > Affixes > Suffixes > Commonly Confused Suffixes > Commonly Confused Suffixes: -er, -or, and -ar
Commonly Confused Suffixes: -er, -or, and -ar
When to use “-er,” “-or,” or “-ar” at the end of a word
The suffixes “-er,” “-or,” and “-ar” are all used to create nouns of agency (indicating “a person or thing that performs an action”) from verbs. Of the three, “-er” is by far the most common, while “-or” is much more common than “-ar.” Because they perform the same function and are pronounced in the same way (/ər/), it can be difficult to decide which suffix is the correct one to use.
When a verb is changed into a noun of agency using a suffix, it will almost always be “-er.” However, there are a few particular conventions we can follow to determine when we should use “-or” instead. (We use the “-ar” suffix much more rarely, so we will discuss it separately toward the end of the section.)
Rule 1: Use “-er” with verbs ending in a single consonant
When a verb ends in a single consonant, it will almost always take the suffix “-er.” Note that if the consonant is preceded by a single vowel, the consonant will generally double before the suffix (though this is not always the case; go to the section Doubling Consonants with Vowel Suffixes to learn more).
For example:
- bat→batter
- barter→barterer
- canvas→canvasser
- cater→caterer
- cheat→cheater
- eat→eater
- embroider→embroiderer
- feel→feeler
- fib→fibber
- format→formatter
- grab→grabber
- loiter→loiterer
- loot→looter
- propel→propeller
- rap→rapper
- read→reader
- scrub→scrubber
- sit→sitter
- shred→shredder
- travel→traveler
- yak→yakker
There are several exceptions to this rule, though:
- conquer→conqueror
- council→councilor
- counsel→counselor
- offer→offeror
- sail→sailor
Rule 1.5: Use “-or” with multi-syllable verbs ending in “-it”
While single-syllable verbs that end in “-it” will usually take the suffix “-er” and have the final T doubled (as in hitter, knitter, quitter, sitter, etc.), verbs with two or more syllables ending in “-it” are much more likely to take the suffix “-or.” For example:
- audit→auditor
- credit→creditor
- edit→editor
- exhibit→exhibitor
- inherit→inheritor
- inhibit→inhibitor
- solicit→solicitor
- visit→visitor
While this convention is fairly reliable, there are some exceptions:
- delimit→delimiter
- profit→profiter
- recruit→recruiter
Also note that this convention does not apply when a silent E follows the final T.
Rule 2: Use “-er” with verbs ending in a silent E
Most verbs that end in a consonant + silent E will take the “-er” suffix (which replaces the final E of the root word). For instance:
- advertise→advertiser
- bake→baker
- bathe→bather
- change→changer
- code→coder
- divide→divider
- frame→framer
- give→giver
- grate→grater
- hate→hater
- love→lover
- make→maker
- organize→organizer
- page→pager
- ride→rider
- slide→slider
- time→timer
- write→writer
This is a reliable convention to follow, but there are some exceptions, most often when a word ends in “-ise”:
- incise→incisor
- previse→previsor
- promise→promisor (variant of promiser, used especially in legal writing)
- supervise→supervisor
- survive→survivor
However, the most consistent exception is for verbs with more than one syllable that end in “-ate.”
Rule 2.5: Use “-or” with multi-syllable verbs ending in “-ate”
When a word has more than one syllable and ends in “-ate,” it will almost always take the “-or” suffix. Once again, the suffix replaces the silent E at the end. For example:
- accelerate→accelerator
- administrate→administrator
- animate→animator
- calculate→calculator
- coordinate→coordinator
- educate→educator
- elevate→elevator
- generate→generator
- instigate→instigator
- liberate→liberator
- motivate→motivator
- narrate→narrator
- perpetrate→perpetrator
- refrigerate→refrigerator
- spectate→spectator
- terminate→terminator
- ventilate→ventilator
Remember, single-syllable verbs ending in “-ate” will take the “-er” suffix, as in grater, hater, skater, etc.
Rule 3: Use “-er” with verbs ending in consonant clusters
So far we’ve mostly looked at examples of verbs that end in a single consonant and a silent E, with a few different instances in which “-or” is (or might) be used instead of “-er.”
However, when a verb ends in a consonant cluster (two or more consonants that quickly blend together in the same syllable), it is much more likely to take the “-er” suffix.
For example:
- adapt→adapter*
- bend→bender
- boost→booster
- build→builder
- busk→busker
- contend→contender
- defend→defender
- dust→duster
- forest→forester
- golf→golfer
- grind→grinder
- help→helper
- jump→jumper
- lend→lender
- mend→mender
- protest→protester
- respond→responder
- shoplift→shoplifter
- tempt→tempter
- weld→welder
However, there are a few common exceptions to this convention:
- invent→inventor
- invest→investor
- sculpt→sculptor
- torment→tormentor
- vend→vendor
(*Adapter can also be spelled adaptor, but this is a bit less common.)
Uniquely, we more commonly use “-or” when a word ends in the cluster CT.
Rule 3.5: Use “-or” with verbs ending in CT
While verbs ending in other consonant clusters will take the “-er” suffix, a verb that ends in CT will almost always be made into a noun with the suffix “-or,” as in:
- abduct→abductor
- act→actor
- conduct→conductor
- contract→contractor
- correct→corrector
- direct→director
- eject→ejector
- instruct→instructor
- object→objector
- project→projector
- react→reactor
- reflect→reflector
- select→selector
Rule 4: Use “-er” with verbs ending in consonant digraphs
Like we do with verbs ending in consonant clusters (other than CT), we use the “-er” suffix with verbs ending in consonant digraphs, pairs of consonants that form a single unique consonant sound. This is also true of words ending in the consonant trigraph TCH.
For example:
- catch→catcher
- choreograph→choreographer
- cough→cougher
- etch→etcher
- laugh→laugher
- march→marcher
- publish→publisher
- sing→singer
- teach→teacher
- wash→washer
- watch→watcher
This is also true when a verb ends in a double consonant (except SS, as we’ll see later). For example:
- bluff→bluffer
- buzz→buzzer
- call→caller
- distill→distiller
- mill→miller
- roll→roller
- spell→speller
- staff→staffer
Rule 4.5: There’s no pattern for verbs ending in SS
While verbs ending in FF, LL, or ZZ will always take the suffix “-er,” there is much less certainty for words ending in SS—there is no clear pattern, so we just have to memorize which suffix a particular word will take.
-er | -or |
|---|---|
address→addresser canvass→canvasser dress→dresser express→expresser guess→guesser hiss→hisser kiss→kisser pass→passer trespass→trespasser | assess→assessor compress→compressor confess→confessor depress→depressor possess→possessor process→processor profess→professor suppress→suppressor transgress→transgressor |
Using the suffix “-ar”
While “-er” is the most common suffix to form nouns of agency from verbs, the suffix “-or” performs the same function in certain instances. However, there is a third suffix that can be used to form these types of nouns, and it is pronounced the same way as the other two: “-ar.”
Nouns of agency ending in “-ar”
Nouns of agency ending in the “-ar” suffix are much less common than “-er” or “-or,” and there is no real convention to dictate when “-ar” is the appropriate ending.
There are only two nouns that can be directly derived from verbs using “-ar”:
- beg→beggar
- lie→liar
There is a third verb that is connected to a noun of agency: burgle→burglar. In this case, however, burglar is the original word (derived from Anglo-Latin) with the verb burgle derived from it, a process known as a “back-formation.”
Finally, there are a few other nouns of agency that end in “-ar,” but they are not derived from or directly connected to a verb, so “-ar” is not functioning as a suffix:
- bursar
- registrar
- scholar
- vicar
Other nouns ending in “-ar”
In addition to ending some nouns of agency, “-ar” appears at the ends of several other common nouns. However, it is not functioning as a suffix in these cases, as it does not change a different part of speech into a noun. For instance:
- altar
- avatar
- calendar
- cheddar
- dollar
- grammar
- guitar
- hangar (meaning “a large building or shelter, usually to house aircraft”; not related to the verb hang)
- mortar
- nectar
- pillar
- radar
- vinegar
Using “-ar” to form adjectives
While the suffix “-ar” is used to form a few nouns, it is much more commonly used to create adjectives, either on its own or as part of the larger suffix “-ular.” (Both “-ar” and “-ular” are used to mean “like; resembling or relating to; of or belonging to.”)
For example:
- angle→angular
- cell→cellular
- circle→circular
- grain→granular
- line→linear
- muscle→muscular
- nucleus→nuclear
- pole→polar
- populace→popular
- title→titular
- vehicle→vehicular
Forming Comparative Adjectives and Comparative Adverbs
While many adjectives can be formed with the suffix “-ar,” it’s important to note that the suffix “-er” is the only ending that can be used to create comparative adjectives and comparative adverbs—adjectives and adverbs used to compare traits between two people or things. For example:
- bright→brighter
- dim→dimmer
- fast→faster
- full→fuller
- happy→happier
- long→longer
- red→redder
- slow→slower
- tall→taller
- witty→wittier
Forming other comparatives
Note that not all adjectives can become comparative by adding “-er.” Only those that have one syllable or those with two syllables ending in “-y” can do so. For longer adjectives, we simply add the words more or less before them, as in:
- admirable→more/less admirable
- careful→more/less careful
- intelligent→more/less intelligent
- loyal→more/less loyal
- respectful→more/less respectful
- vivid→more/less vivid
Adverbs also have this restriction, though it is only single-syllable adverbs that can take the “-er” suffix; adverbs ending in “-y” are almost always formed by adding “-ly” to adjectives, and they take the words more/less to become comparative. For example:
- admirably→more/less admirably
- carefully→more/less carefully
- intelligently→more/less intelligently
- loyally→more/less loyally
- respectfully→more/less respectfully
- vividly→more/less vividly
Other adjectives are simply irregular, and have a specific comparative form that does not follow the convention above; here are some of the most common examples:
Adjectives | Adverbs |
|---|---|
bad→worse fun→more/less fun far→farther (literal distance) or further (figurative distance) good→better little→less (when describing an amount) | badly→worse early→earlier* far→farther (literal distance) or further (figurative distance) little→less (when describing an amount) well→better |
(*Early is both an adjective and an adverb, and it has the same comparative form in both uses: earlier. This is irregular only as an adverb because it goes against the convention of adding more/less to adverbs ending in “-ly.”)
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