Origin: 1175–1225; ME; OE
heardlice. See hard, -ly 
Synonyms:
1. Hardly, barely, scarcely imply a narrow margin by which performance was, is, or will be achieved. Hardly, though often interchangeable with scarcely and barely, usually emphasizes the idea of the difficulty involved: We could hardly endure the winter. Barely emphasizes the narrowness of the margin of safety, “only just and no more”: We barely succeeded. Scarcely implies a very narrow margin, below satisfactory performance: He can scarcely read.
Usage note:1, 3. Hardly, barely, and
scarcely all have a negative connotation, and the use of any of them with a negative like
can't or
couldn't is often condemned as a double negative and thus considered nonstandard:
I can't hardly wait. Such constructions do occur occasionally in the speech of educated persons, often with jocular intent (
You can't hardly get that kind any more) but are not found in formal speech or writing. When
hardly in the sense “only just, almost not” is followed by a clause, the usual word to introduce the clause is
when: The telephone had hardly stopped ringing when (not
than)
the doorbell rang. See also double negative.