Longman Dictionary of Contemporary English - lapse

~1 n 1 a short time when someone is careless or forgetful + in  (There haven't been any lapses in security recently.) + of  (A single lapse of concentration cost Becker the game. | a memory lapse (=when you cannot remember something for a short time)) 2 a failure to do something you should do, especially to behave correctly  (He didn't offer Darren a drink and Marie did not appear to notice the lapse.) 3 C usually singular a period of time between two events  (The usual time lapse between request and delivery is two days.) + of  (a lapse of about ten seconds) ~2 v 1 to gradually come to an end or to stop for a period of time  (I let the conversation lapse and Kelly finally spoke up.) 2 if a contract, agreement, legal right etc lapses, it comes to an end, for example because an agreed time limit has passed lapse into sth phr v 1 lapse into silence/sleep/a daydream etc to go into a quiet or less active state  (The girl lapsed into a sulky silence. | He lapsed into a coma and died two days later.) 2 to start behaving or speaking in a different and usually less good or acceptable way  (Following his death, the Empire lapsed into chaos. | She would sometimes deliberately lapse into another dialect.)