"Lose track of time" means "to be unaware of what time it is". Example: Every time Matthew goes to the library, he loses track of time. Once he stayed there for 8 hours! #idiom #idioms #slang #saying #sayings #phrase #phrases #expression #expressions #english #englishlanguage #learnenglish #studyenglish #language #vocabulary #efl #esl #tesl #tefl #toefl #ielts #toeic #time