Yes, single is a Scrabble word!

Verb

1. Hit a single

Adjective

1. Being or characteristic of a single thing or person

2. Used of flowers having usually only one row or whorl of petals

3. Existing alone or consisting of one entity or part or aspect or individual

4. Not married or related to the unmarried state

5. Characteristic of or meant for a single person or thing

6. Having uniform application

7. Not divided among or brought to bear on more than one object or objective

Noun

1. A base hit on which the batter stops safely at first base

2. The smallest whole number or a numeral representing this number