What is the meaning of あい?

mutual, together, each other

used in official or epistolary writings for elegance or politeness

mutual, together, each other, meeting

Short for 合い服 (あいふく, aifuku, clothing worn in spring or autumn).

interval of time or space; time; during; between; leisure

relation; relationship; terms (between people)

Short for 間狂言 (aikyōgen).

Short for 間駒 (aigoma).

Short for 間の手 (ai no te).

Clipping of はい (hai).

: ant

Source: wiktionary.org