SKIM, noun (a different orthography of scum;

Scum; the thich matter that forms on the surface of a liquor.

SKIM, verb transitive

1. To take off the thick gross matter which separates from any liquid substance and collects on the surface; as, to skim milk by taking off the cream.

2. To take off by skimming; as, to skim cream.

3. To pass near the surface; to brush the surface slightly.

SKIM, verb intransitive

1. To pass lightly; to glide along in an even smooth course, or without flapping; as, an eagle or hawk skims along the etherial regions.

2. To glide along near the surface; to pass lightly.

3. To hasten over superficially or with slight attention.

They skim over a science in a superficial survey.