Meaning of FLANK in English
The files that do not belong to the centre, that is the a, b and c files on the queenside, and the f, g and h files on the kingside. Certain openings that focus on flank development are called "flank openings." Typical first moves for these openings are 1.c4; 1.b3; 1.Nf3; etc.
English glossary of chess terms. Английский глоссарий шахматных терминов. 2012