① blow
② play (wind instruments)
③ boast, brag

HSK –

STROKES – 4

RADICAL – 口

Elements  —-  An open mouth 欠 + a mouth 口. Phonetic series 欠.

An open mouth 欠 expels air 口, blowing, playing a wind instrument, or boasting. Here the mouth radical is only used to stress the meaning of a mouth expeling air, but also to refine the meaning, as all these meanings are special activities of a mouth expeling air, or show specific situations in which this aire is expelled.

From Exhale > play musical instrument > boast (perhaos of playing goog music) > break up (as a flame blowed up).

吹牛 chuīniú brag, boast.

Though in its origin this character, even being related to a person, has a not so clear relation with the character for person 人, now, the evolution of language made it similar. In the upper part of the person a «cubist» representation of an open mouth has been added.

This is a person yawning, or perhaps a person with the mouth open who feels a lack of air. Later it was used for other situations in which there is a lack of something, as to lack something, to be deficent in something, to owe money, etc.