Д-309

ДРУГ ДРУГА (ДРУЖКУ coll) ДРУГ ДРУГУ (ДРУЖКЕ coll) ДРУГ НА ДРУГА (НА ДРУЖКУ coll) ДРУГ О ДРУГЕ (О ДРУЖКЕ coll) и т. п. NP (has no nom case) sing only fixed WO

each of two or more (people, things etc) does sth. to the other(s) (used to indicate a reciprocal action or relationship): (to (about, against, near etc)) each other (one another)

one after (against, over, without etc) the other (in limited contexts) each othert

one another'. Они впервые стояли рядом - зять и свояк. За столом они не сказали друг дружке ни слова (Абрамов 1). It was the first time they had stood side by side-as brothers-in-law. They had not said a word to each other at the table (1a).

«Доктор! Решительно нам нельзя разговаривать: мы читаем в душе друг у друга» (Лермонтов 1). "Upon my word, Doctor, it's impossible for us to talk together. We read each other's minds" (lc).

...Друг» is the short form of the adjective «другой».