What does overslept mean?

[Lola]

English Grammar Error, Intermediate level

ESL/EFL Test #15 "Sleep well (1)", question 4

On one occasion to her shame she slept over.

(a) On
(b) to
(c) slept over

English Grammar Error, Intermediate level

ESL/EFL Test #15 "Sleep well (1)", answer 4

On one occasion to her shame she overslept.

Correct entry: overslept
The error was: (c) slept over
_________________________

what does overslept mean?

[Mister Micawber]

.
Overslept = slept past the intended waking time.
Slept over = stayed overnight at another's home.
.
_________________
Native English teacher at Mister Micawber's