Noun:

A drop in the level of the uterus during the last weeks of pregnancy as the head of the fetus engages in the pelvis.

Verb:

[1] To make or become lighter in weight, pressure or sensitivity.

[2] To make or become more cheerful or less serious.

[3] To make or become lighter or brighter.

[4] To emit flashes of lightning; flash with lightning. (rare)

None of these things is similar to charging your iPhone.