noun, noun which may take the genitive case particle 'no'
unusual; exceptional; phenomenal
Describes something that stands out as remarkably different from the norm, often in a positive or noteworthy way. Used as a noun or with の to modify another noun.
彼の才能は異数だ。
His talent is exceptional.
今年の夏の暑さは異数の暑さだった。
This summer's heat was unusually intense.