rirci gismu

x₁ [member] is rare/unusual/uncommon/atypical in property x₂ (ka) among members of x₃ (set).

(x₃ is complete specification of set); (cf. cizra, fadni, cafne, kampu, cnano - the generalized opposite to any/all of these concepts)

In notes:

cafne: x₁ (event) often/frequently/commonly/customarily occurs/recurs by standard x₂.
cizra: x₁ is strange/weird/deviant/bizarre/odd to x₂ in property x₃ (ka).
cnano: x₁ [value] is a norm/average in property/amount x₂ (ka/ni) among x₃(s) (set) by standard x₄.
fadni: x₁ [member] is ordinary/common/typical/usual in property x₂ (ka) among members of x₃ (set).
kampu: x₁ (property - ka) is common/general/universal among members of set x₂ (complete set).
nalfadni: f₁ [member] is uncommon/atypical/unusual in property f₂ (ka) among members of f₃ (set).
zilrirci: The property x₁ is rare/unusual/uncommon among x₂