Yes, one is a Scrabble word!

Adjective

1. Used of a single unit or thing; not two or more

2. Having the indivisible character of a unit

3. Of the same kind or quality

4. Used informally as an intensifier

5. Indefinite in time or position

6. Being a single entity made by combining separate components

7. Eminent beyond or above comparison

Noun

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

2. A single person or thing