(MOMENT) [noun] [U] [informal] - (used mainly in spoken English) a short period of time; a moment"Come on! We're going to be late." "Hang on a mo! I just get my wallet."I'll be with you in half a mo (= very soon).See also the Big Mo at big (IMPORTANT).
MO
Meaning of MO in English
Cambridge English vocab. Кембриджский английский словарь. 2012