summertime
Multiple Entries:summertime summer time
Concise Oxford English Dictionary © 2008 Oxford University Press:
summertime/ˈsʌmətʌɪm/
▶noun the season or period of summer.
Concise Oxford English Dictionary © 2008 Oxford University Press:
summer time
▶noun Brit. time as advanced one hour ahead of standard time to achieve longer evening daylight in summer.
'summertime' also found in these Oxford entries:

