infrequent
Concise Oxford English Dictionary © 2008 Oxford University Press:
infrequent/ɪnˈfriːkwənt/
▶adjective not occurring often; rare.
– derivatives
infrequency noun,
infrequently adverb.
infrequency noun,
infrequently adverb.
'infrequent' also found in these Oxford entries:

