From The Collaborative International Dictionary of English v.0.48 :
lunchtime \lunchtime\ n.
the time for eating lunch; as, he observed a regular
lunchtime.
[WordNet 1.5]
From WordNet (r) 3.0 (2006) :
lunchtime
n 1: the customary or habitual hour for eating lunch; "he
observed a regular lunchtime" [syn: lunchtime, lunch
period]