What is Undrained?

Undrained definition and meaning on Dictionary terms:
verb (used with object)

to withdraw or draw off (a liquid) gradually; remove slowly or by degrees, as by filtration: to drain oil from a crankcase.
to withdraw liquid gradually from; make empty or dry by drawing off liquid: to drain a crankcase.
to exhaust the resources of: to drain the treasury.
to deprive of strength; tire.