Yes, label is a Scrabble word!

Verb

1. Assign a label to; designate with a label

2. Attach a tag or label to

3. Pronounce judgment on

4. Distinguish (as a compound or molecule) by introducing a labeled atom

5. Distinguish (an element or atom) by using a radioactive isotope or an isotope of unusual mass for tracing through chemical reactions

Noun

1. A brief description given for purposes of identification

2. Trade name of a company that produces musical recordings

3. A radioactive isotope that is used in a compound in order to trace the mechanism of a chemical reaction

4. An identifying or descriptive marker that is attached to an object