One commonly heard kind of flat adverb is an adverb which is identical to its adjective. No -ly is added to the adjective form. Examples include
- He drives too slow.
- That midfielder runs fast.
- The student arrived late to class.
- She dressed smart for the job interview.
Another common kind of flat adverb has no -ly form. Some of the adverbs we use the most have no -ly form, such as
- I am not ready for bed.
- I always eat breakfast.
- Go now before it rains.
Flat adverbs with no -ly form are acceptable in standard English usage. Flat adverbs identical to adjectives are growing in acceptance, but are not universally accepted.
I suspect older people, who were taught grammar rigorously, startle when they hear younger people drop the -ly on some adverbs. And I suspect younger people, whose grammar education was not rigorous, are not aware there is another way to say, “He ran quick as can be.”
English is a living language, and like all living things, grows, changes, and adapts. American English has become less formal than British English and less formal than the English of past generations of Americans.
I see two problems with flat adverbs. One is an older generation judging a younger generation as poorly educated if the younger people drop the -ly on adverbs. Since usually it’s an older generation hiring and promoting a younger generation, using flat adverbs during interviews and emails could reflect badly on younger applicants.
Another problem is what the SAT and ACE expect of students taking those tests. Standard English changes, but slowly (not slow).






