n. 25B6; noun HOLLOW, depression, dip, dent, dint, cavity, concavity, pit, trough; dimple, cleft; snick, nick, notch; recess, bay, inlet, cove.
INDENTATION
Meaning of INDENTATION in English
Concise Oxford thesaurus English vocabulary. Краткий оксфордский словарь английского языка тезаурус. 2012