Misspelling of 欸乃.

at; in; on

careful; cautious; diligent

dangerous / precipitous / difficult / perilous / risky / challenging

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”).

hail (precipitated ice) / ice (frozen water)

one, 1

the fourth of the ten Heavenly Stems