calends
Concise Oxford English Dictionary © 2008 Oxford University Press:
calends /ˈkalɪndz/ (also kalends)
▶plural noun the first day of the month in the ancient Roman calendar.
– origin OE (denoting an appointed time): from OFr. calendes, from L. kalendae, calendae ‘first day of the month’ (when the order of days was proclaimed).
'calends' also found in these Oxford entries:

