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general::
Phrase(s): let something slip by [and] let something slide by
1. Lit. to permit something to move quickly by oneself. • He let the ball slip by and he knew he had better get the next one. • The careless cashier let the leaky milk carton slide by. 2. Fig. to forget or miss an important time or date. • I’m sorry I just let your birthday slip by. • I let it slide by accidentally. 3. Fig. to waste a period of time. • You wasted the whole day by letting it slip by. • We were having fun, and we let the time slide by.
McGrawhill's American Idioms And Phrasal Verbs