adj, verb ·Rare ·Advanced level

Definitions

Verb

1. 1
   To loose; release. transitive

Adjective

1. 1
   Not fast or safe; not secure.

Etymology

Etymology 1

From Middle English unfasten, unvesten, onfesten, equivalent to un- + fast.

Etymology 2

From un- + fast.

Data sourced from Wiktionary, WordNet, CMU, and other open linguistic databases. Updated March 2026.