na-adjective
unbounded
Mathematical term describing a set, function, or sequence that is not bounded; used in analysis, topology, and related fields.
この数列は非有界である。
This sequence is unbounded.
非有界な集合の例を挙げてください。
Please give an example of an unbounded set.
無限 means 'infinite', which is related but not identical; an unbounded set may be finite or infinite, while 無限 specifically refers to infinite extent or quantity.
Compound of 非 (hi, 'non-') + 有界 (yūkai, 'bounded'). The term 有界 is itself a mathematical coinage from 有 (yū, 'have') + 界 (kai, 'boundary').