General: Flat adverbs and what happened to LY?

Have you heard someone recently say Drive Safe ? If you’re my age, I’m sure that grates on you somewhat. In the end, safe is an adjective, but here it’s being used as an adverb. If I’d said that at school, I would have been corrected and told it should have been Drive Safely.

Similarly, today I was watching the UK Lingo TV show . I really like it and generally, I hear quite correct English on it, particularly from the presenter. But I then heard him say He did brilliant. And immediately I had the same guttural reaction to it.

What ever happened to LY?

So, if this has happened to you as well, you aren’t imagining things. Curiously, using adjectives as adverbs is incredibly common. However, the ly hasn’t vanished.

Formally, these are known as flat adverbs, which have functioned alongside their ly versions, apparently for centuries.

Flat Adverbs

Flat adverbs are adverbs that share the exact same spelling as their corresponding adjective form. In fact, in Old English, adverbs were commonly formed without ly. And we still use many of them today without even thinking. Words like fast, hard, and late have always been acceptable as adverbs.

We don’t say I worked fastly or She worked hardly or They worked lately. The first one would just sound odd, and in fact the last two would infer an entirely different meaning.

So where did the ly come from?

In the 18th century, traditional grammarians tried to standardise English by prescribing the ly suffix to formally distinguish adverbs from adjectives.

So, it was quite intentional.

Today though, expressions like drive safe (vs. drive safely) are widely debated, even though both are used in everyday casual communication. The team at Merriam-Webster classify safe in this context as a valid flat adverb.

Others argue that safe functions as an adjective describing the condition of the driver upon arrival, rather than the manner of driving. Sorry, but I don’t buy this explanation.

Still, for formal writing or grammar tests, purists and style guides generally still prefer drive safely.

What about “He did brilliant”?

Using brilliant for brilliantly is clearly highly colloquial. But it’s part of a larger trend where casual English drops the ly suffix, arguably for efficiency.

I now commonly hear versions that don’t sit well with me, like She played good and He ran quick. I’m sure it’s based on the response I would have received at school if I’d said things this way.

So is ly gone?

I don’t think so. I suspect that while removing it might be accepted in conversational speech, formal English still strictly requires the adverb form (He did brilliantly, She played well, He ran quickly).

Do you still use ly?

2026-08-22