-mo

Collins Concise English Dictionary © HarperCollins Publishers::

-mo suffix:forming_nouns

1. (in bookbinding) indicating book size by specifying the number of leaves formed by folding one sheet of paper: 12mo, twelvemo, or duodecimo, 16mo or sixteenmo

Etymology: abstracted from duodecimo

WordReference Random House Unabridged Dictionary of American English © 2026

mo  (mō), n. [Informal.]

1. Informal Terms moment (def. 1).

• by shortening

-mo, 

1. Printing a suffix occurring in a series of compounds that describe book sizes according to the number of leaves formed by the folding of a single sheet of paper:
   sixteenmo.

• combining form extracted from duodecimo

MO, 

1. method of operation.
2. Place Names Missouri (approved esp. for use with zip code).
3. mode of operation.
4. modus operandi.

Mo, [Symbol, Chem.]

1. Chemistry molybdenum.

Mo., 

1. Place Names Missouri.
2. Monday.

mo., 

1. pl. mos. month.
2. months.

M.O., 

1. mail order.
2. manually operated.
3. Medical Officer.
4. method of operation.
5. mode of operation.
6. modus operandi.
7. money order.

m.o., 

1. mail order.
2. modus operandi.
3. money order.