[1] : The Collaborative International Dictionary of English v.0.48

ultimo \ul"timo\ l. ultimo mense in the last month.
   in the month immediately preceding the present; as, on the
   1st ultimo; -- usually abbreviated to ult. cf. proximo.
   1913 webster
see also:
proximo 

[2] : WordNet (r) 2.0

ultimo
     adj : in or of the month preceding the present one; "your letter
           received on the 29th ult" syn: ult
see also:
ult 

Ultimo >> U Words
Ultimo, definition of term: Ultimo
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