Definitions
1.VerbTo leave (school, a race, etc.) prematurely and voluntarily."Nothing went well in high school, so he dropped out."
2.VerbTo opt out of conventional society.
3.VerbTo be lost or momentarily interrupted."I can't make phone calls because the line keeps dropping out."
4.VerbUsed other than figuratively or idiomatically: see drop, out.
5.VerbTo give way under someone."The board he was walking on dropped out."
6.VerbTo cause someone to slip and/or fall down."The ground dropped out from under him.; When she left him, his world dropped out beneath him."
7.VerbTo dismiss, break up with or abandon (someone).