Yes, size is a Scrabble word!

Verb

1. Cover or stiffen or glaze a porous material with size or sizing (a glutinous substance)

2. Sort according to size

3. Make to a size; bring to a suitable size

Adjective

1. (used in combination) sized

Noun

1. The physical magnitude of something (how big it is)

2. The property resulting from being one of a series of graduated measurements (as of clothing)

3. Any glutinous material used to fill pores in surfaces or to stiffen fabrics

4. The actual state of affairs

5. A large magnitude