english
1
general::
From time to time, now and then, as in Nell has been known to eat meat on occasion. This usage, first in the form of upon occasion, replaced by occasion about 1600.
American Heritage Idioms
2
general::
Phrase(s): on occasion occasionally. • I like to go to the movies on occasion. • On occasion, Mary would walk her dog through the park.
McGrawhill's American Idioms And Phrasal Verbs