external; separable from the thing itself; inessential
not belonging to something; outside
An external factor
A card whose effects persist beyond the turn on which it is played.
A chemical hair treatment imparting or removing curliness, whose effects typically last for a period of weeks; a perm.
Given an n⨯n matrix a_ij,, the sum over all permutations 𝜋, of ∏ᵢ₌₁ⁿa_i𝜋(i).
Without end, eternal.
Lasting for an indefinitely long time.