Hardly means almost not at all. I could hardly hear her. There is hardly any milk left. It is a negative word, and that is the whole difficulty with it.
Because it is already negative, it does not take another negative: I can hardly see, never I cannot hardly see. It also inverts the verb when it starts a sentence — hardly had we sat down when the phone rang — which is a formal construction worth recognising. And hardly is not the adverb of hard: working hard and hardly working mean opposite things, and that joke is the best way to remember it. Hardly ever means almost never.
1adverbhardlyAlmost not at all.
“There is hardly anything in the fridge.”
2adverbcertainlyUsed to say something is certainly not the case.
“It is hardly a surprise after all that.”
3adverbimmediatelyOnly just, and immediately before something else happened.
“We had hardly arrived when they asked us to leave.”
Too few real examples of this word to estimate which sense is commonest.
hardly is a degree adverb.
Also accepted in games: barely, scarcely
Old English heardlice meant firmly or with difficulty, and hardly kept the difficulty and lost the firmness. The modern meaning came by way of with difficulty — if you can only just do a thing, you can hardly do it — and the slide from just barely to almost not at all took a few centuries.
Old English
heardlīċe — boldly; hardily; without ease; in a way that causes pain; not easily; only by degrees
Middle English
hardely
English, today
hardly
From Middle English hardely, hardliche, from Old English heardlīċe (“boldly; hardily; without ease; in a way that causes pain; not easily; only by degrees”), equivalent to hard + -ly. Compare Dutch hardelijk, German härtlich.
Etymology from Wiktionary, CC BY-SA