What does "microexpression" mean?

A fleeting, involuntary facial expression that may reveal private thoughts or emotions.

How do you pronounce "microexpression"?

Pronounced //ˌmaɪkɹəʊ.ɪkˈspɹɛʃən//.

Common synonyms include: brief facial cue, brief nonverbal cue, emotion cue, fleeting expression, involuntary cue, involuntary expression.

/ˌmaɪkɹəʊ.ɪkˈspɹɛʃən/ noun

noun ·Rare ·Advanced level

Noun

1
A fleeting, involuntary facial expression that may reveal private thoughts or emotions.

From micro- + expression.