affair

n. amour, lovers' affair; matter; incident; deal, concern

An affair may refer to a form of nonmonogamy, to infidelity or to adultery. Where an affair lacks both overt and covert sexual behaviour and yet exhibits intense or enduring emotional intimacy it is called an emotional affair. 'Affair' may be used as a euphemism and in some cases to add glamour to an illicit liaison or it may be used to slander.
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Noun
1. a vaguely specified concern; "several matters to attend to"; "it is none of your affair"; "things are going well"
(synonym) matter, thing
(hypernym) concern
2. a usually secretive or illicit sexual relationship
(synonym) affaire, intimacy, liaison, involvement, amour
(hypernym) sexual relationship
3. a vaguely specified social event; "the party was quite an affair"; "an occasion arranged to honor the president"; "a seemingly endless round of social functions"
(synonym) occasion, social occasion, function, social function
(hypernym) social event
(hyponym) party

(n.)
That which is done or is to be done; matter; concern; as, a difficult affair to manage; business of any kind, commercial, professional, or public; -- often in the plural. "At the head of affairs." Junius.
  

(n.)
Any proceeding or action which it is wished to refer to or characterize vaguely; as, an affair of honor, i. e., a duel; an affair of love, i. e., an intrigue.
  

(n.)
An action or engagement not of sufficient magnitude to be called a battle.
  

(n.)
Action; endeavor.
  

(n.)
A material object (vaguely designated).
  

zui3 shang4 mei2 mao2, ban4 shi4 bu4 lao2
If he has no hair above the mouth, he is not trustworthy to handle affairs.
A man too young to grow a beard is not dependable. Alternative form: 嘴上无毛，办事不牢 (zui3 shang4 wu2 mao2, ban4 shi4 bu4 lao2).