8 letters · 19 points in Scrabble
noun a close friend who accompanies his buddies in their activities
originFrom side + kick, which in the late 19th and early 20th century was a slang term for the front side pocket of a pair of trousers, known as the pocket safest from theft. Thus, by analogy, a "side-kick" was a person's closest companion.
Etymology from Wiktionary, CC BY-SA 3.0