Yes, square is a Scrabble word!

Adverb

1. In a straight direct way

2. In a square shape

3. Firmly and solidly

Verb

1. Make square

2. Raise to the second power

3. Cause to match, as of ideas or acts

4. Position so as to be square

5. Be compatible with

6. Pay someone and settle a debt

7. Turn the paddle; in canoeing

8. Turn the oar, while rowing

Adjective

1. Having four equal sides and four right angles or forming a right angle

2. Characterized by honesty and fairness

3. Providing abundant nourishment

4. Leaving no balance

5. Without evasion or compromise

6. Rigidly conventional or old-fashioned

Noun

1. (geometry) a plane rectangle with four equal sides and four right angles; a four-sided regular polygon

2. The product of two equal terms

3. An open area at the meeting of two or more streets

4. Something approximating the shape of a square

5. Someone who doesn't understand what is going on

6. A formal and conservative person with old-fashioned views

7. Any artifact having a shape similar to a plane geometric figure with four equal sides and four right angles

8. A hand tool consisting of two straight arms at right angles; used to construct or test right angles