not determinate; not precisely fixed in extent; indefinite; uncertain.

not clear; vague.

not established.

not settled or decided.

Mathematics .

(of a quantity) undefined, as 0/0.

(of an equation) able to be satisfied by more than one value for each unknown.

Botany . (of an inflorescence) having the axis or axes not ending in a flower or bud, thus allowing further elongation.

Mathematics . something whose value is not specified

used esp. in abstract algebra; a variable.