ultimo

UK: /ˈʌltɪˌməʊ/ US: (ul′tə mō′)

WordReference Random House Unabridged Dictionary of American English © 2026

ul•ti•mo  (ul′tə mō′), adv. 

1. in or of the month preceding the current one:
   on the 12th ultimo. Abbr.:
   ult., ulto. Cf. instant (def. 11), proximo. 

• Latin ultimō (mēnse or diē) in the last (month) or on the last (day)
• 1575–85

Collins Concise English Dictionary © HarperCollins Publishers::

ultimo / ˈʌltɪˌməʊ/ adverb

1. (esp abbreviated in formal correspondence) in or during the previous month: a letter of the 7th ultimo
   Abbreviation: ult.
   Compare instant7, proximo

Etymology: 16th Century: from Latin ultimō on the last