- unworldly (adj.)
- 1707, from un- (1) "not" + worldly (adj.). Related: Unworldliness.
- time-span (n.)
- also timespan, 1897, from time (n.) + span (n.1).
- undeserving (adj.)
- 1540s, from un- (1) "not" + present participle of deserve (v.).
- undeterred (adj.)
- c. 1600, from un- (1) "not" + past participle of deter (v.).
- undecisive (adj.)
- 1660s, from un- (1) "not" + decisive. The usual word is indecisive.
- undecipherable (adj.)
- 1758, from un- (1) "not" + decipherable (see decipher (v.)).
- undiluted (adj.)
- 1756, from un- (1) "not" + past participle of dilute (v.).
- undiminished (adj.)
- 1580s, from un- (1) "not" + past participle of diminish (v.).
- undoubtable (adj.)
- early 15c., from un- (1) "not" + doubt (v.) + -able. Related: Undoubtably.
- unemancipated (adj.)
- 1775, from un- (1) "not" + past participle of emancipate (v.).
- unending (adj.)
- 1660s, from un- (1) "not" + present participle of end (v.).
- unenthusiastic (adj.)
- 1805, from un- (1) "not" + enthusiastic (adj.). Related: Unenthusiastically.
- unenviable (adj.)
- 1640s, from un- (1) "not" + enviable (adj.). Related: Unenviably.
- unevitable (adj.)
- from un- (1) "not" + evitable. The usual word is inevitable. Related: Unevitably.
- unexplainable (adj.)
- 1711, from un- (1) "not" + explain + -able. Related: Unexplainably.
- unexpurgated (adj.)
- 1882, from un- (1) "not" + past participle of expurgate (v.).
- unfaltering (adj.)
- 1660s, from un- (1) "not" + present participle of falter (v.). Related: Unfalteringly.
- unfathomed (adj.)
- 1620s, from un- (1) "not" + past participle of fathom (v.).
- unflagging (adj.)
- 1715, from un- (1) "not" + present participle of flag (v.). Related: Unflaggingly.
- unforeseeable (adj.)
- 1670s, from un- (1) "not" + foreseeable (see foresee). Related: Unforeseeably.
- unfortune (n.)
- "misfortune, bad luck," early 15c., from un- (1) "not" + fortune (n.).
- unhampered (adj.)
- 1690s, from un- (1) "not" + past participle of hamper (v.).
- unheeded (adj.)
- 1610s, from un- (1) "not" + past participle of heed (v.).
- unhelpful (adj.)
- 1590s, from un- (1) "not" + helpful. Related: Unhelpfully; unhelpfulness.
- unheralded (adj.)
- 1845, from un- (1) "not" + past participle of herald (v.).
- unhindered (adj.)
- 1610s, from un- (1) "not" + past participle of hinder (v.).
- unleavened (adj.)
- 1520s, from un- (1) "not" + past participle of leaven (v.).
- unincorporated (adj.)
- 1715, from un- (1) "not" + past participle of incorporate (v.).
- uninflected (adj.)
- 1713, from un- (1) "not" + past participle of inflect (v.).
- uninitiated (adj.)
- 1670s, from un- (1) "not" + past participle of initiate (v.).
- unintelligent (adj.)
- c. 1600, from un- (1) "not" + intelligent (adj.). Related: Unintelligently.
- unintended (adj.)
- 1640s, from un- (1) "not" + past participle of intend (v.).
- unintentional (adj.)
- 1701, from un- (1) "not" + intentional (adj.). Related: Unintentionally.
- uninteresting (adj.)
- "not capable of exciting interest," 1769, from un- (1) "not" + interesting.
- unmanageable (adj.)
- 1630s, from un- (1) "not" + manageable (adj.). Related: Unmanageably; unmanageableness.
- unmarred (adj.)
- c. 1200, from un- (1) "not" + past participle of mar (v.).
- unmeasurable (adj.)
- late 14c., from un- (1) "not" + measurable (adj.). Related: Unmeasurably.
- unmediated (adj.)
- 1640s, from un- (1) "not" + past participle of mediate (v.).
- unmerciful (adj.)
- late 15c., from un- (1) "not" + merciful (adj.). Related: Unmercifully.
- unmet (adj.)
- c. 1600, from un- (1) "not" + past participle of meet (v.).
- unmistakable (adj.)
- 1660s, from un- (1) "not" + mistake (v.) + -able. Related: Unmistakably.
- unneeded (adj.)
- 1725, from un- (1) "not" + past participle of need (v.).
- unnoticed (adj.)
- 1720, from un- (1) "not" + past participle of notice (v.).
- unobtainable (adj.)
- 1775, from un- (1) "not" + obtainable (adj.). Related: Unobtainability.
- unorganized (adj.)
- 1680s, from un- (1) "not" + past participle of organize (v.).
- unostentatious (adj.)
- 1747, from un- (1) "not" + ostentatious (adj.). Related: Unostentatiously.
- unperceived (adj.)
- mid-14c., from un- (1) "not" + past participle of perceive (v.).
- unplanned (adj.)
- by 1804, from un- (1) "not" + past participle of plan (v.).
- unpremeditated (adj.)
- 1590s, from un- (1) "not" + past participle of premeditate (v.).
- unpropitious (adj.)
- c. 1600 (implied in unpropitiously), from un- (1) "not" + propitious (adj.).
