/ˈlaɪflaɪn/
life·line
BrE /ˈlaɪflaɪn/
NAmE /ˈlaɪflaɪn/
a line or rope thrown to rescue sb who is in difficulty in the water
a line attached to sb who goes deep under the sea
something that is very important for sb and that they depend on
The extra payments are a lifeline for most single mothers.