1
general::
Phrase(s): count off
[for a series of people, one by one] to say aloud the next number in a fixed sequence. • The soldiers counted off by threes. • The sergeant told them to count off., Phrase(s): count someone or something off
to count people or things, to see if they are all there. (See also count off.) • Let’s count them off to see who’s missing. • Count off each person, one by one. • I counted each one off.
McGrawhill's American Idioms And Phrasal Verbs
2
general::
1. Count aloud from one end of a line of persons to the other, each person counting in turn. For example, The soldiers counted off one by one. This usage and the practice it describes come from the military. 2. Place in a separate group by counting, as in The office counted off the telephone books for each delivery route.
American Heritage Idioms