Yes, frank is a Scrabble word!

Verb

1. Stamp with a postmark to indicate date and time of mailing

2. Exempt by means of an official pass or letter, as from customs or other checks

Adjective

1. Characterized by directness in manner or speech; without subtlety or evasion

2. Clearly manifest; evident

Noun

1. A member of the ancient Germanic peoples who spread from the Rhine into the Roman Empire in the 4th century

2. A smooth-textured sausage of minced beef or pork usually smoked; often served on a bread roll