Hard adv. 1. Strenuously; with all one’s force; energetically and persistently; with vigor and strength; e.g. to work.~. 2. So as to be hard, firm, e.g. to freeze ~.
3. With difficulty,, painfully, e.g. to die ~ (1 — to fighf for one’s life to the very end; 2 — to die painfully).
Hardly adv. 1. Only just; not quite; barely, scarcely, e.g. I ~ know her (have only a very slight acquaintance with her); she is ~ twenty-one years old; he had ~ time; I’m so tired I can ~ walk; ~ had we arrived there when it began to rain; we had ~ arrived when it began to rain. 2. Used to suggest that smth. is improbable, unlikely, or unreasonable, e.g. it is ~ possible; he can ~ have arrived yet; you can ~ expect me to do it again. 3. (negative in meaning) Almost no, almost not, e.g. he ~ ever (very seldom) goes to bed before midnight; I need ~ say (it is almost unnecessary for me to say) that I am innocent; there’s ~ any coal left; ~ anybody (very few people).
The two adverbs, hard and hardly are often confused by Russian learners, especially in phrases like to work (study, try, think, etc.) hard. This confusion is brought about by the interfering influence both of Russian and English: the Russian words упорно, энергично, старательно, which correspond to the adverb hard are adverbs, and most adverbs in English are formed with the help of the suffix -ly. Thus the adverb hardly (едва, едва ли, насилу, с трудом) is erroneously used instead of hard. Besides the adverb hard there is a homonymous adjective hard (твердый, тяжелый, крепкий, суровый) which has a different sphere of application and is never confused with hardly.