Again and again

once more; another time; anew; in addition:
will you spell your name again, please?
in an additional case or instance; moreover; besides; furthermore.
on the other hand:
it might happen, and again it might not.
back; in return; in reply:
to answer again.
to the same place or person:
to return again.
again and again, with frequent repet-tion; often:
they went over the same arguments again and again.
as much again, twice as much:
she earns as much again as i do.
adverb
another or second time; once more; anew: he had to start again
once more in a previously experienced or encountered place, state, or condition: he is ill again, he came back again
in addition to the original amount, quant-ty, etc (esp in the phrases as much again; half as much again)
(sentence modifier) on the other hand: he might come and then again he might not
besides; also: she is beautiful and, again, intelligent
(archaic) in reply; back: he answered again to the questioning voice
again and again, continuously; repeatedly
(used with a negative) (caribbean) any more; any longer: i don’t eat pumpkin again
sentence connector
moreover; furthermore: again, it could be said that he is not dead
adv.

late old english agan, from earlier ongean “toward, opposite, against, in exchange for,” from on “on” (see on) + -gegn “against, toward,” compounded for a sense of “lined up facing, opposite,” and “in the opposite direction, returning.” for -gegn, cf. old norse gegn “straight, direct;” danish igen “against;” old frisian jen, old high german gegin, german gegen “against, toward,” entgegen “against, in opposition to.”

in old english, eft was the main word for “again” (see eftsoons), but this often was strengthened by ongean, which became the princ-p-l word by 13c. norse influence is responsible for the hard -g-. differentiated from against 16c. in southern writers, again becoming an adverb only, and against taking over as preposition and conjunction, but again clung to all senses in northern and scottish dialect (where against was not adopted).
repeatedly, often, as in i’ve told you again and again, don’t turn up the heat. this idiom uses repet-tion for the purpose of emphasis (as does its synonym, over and over). shakespeare used it in oth-llo (1:3): “i have told thee often, and i retell thee again and again.” [ c. 1600 ]
in addition to the idiom beginning with
again
also see:

come again
do something over again
ever and again
every now and again
here someone goes again
now and again
off and on (off again, on again)
over again
something else again
time and time again
you can say that again