All 16 words, sorted alphabetically. Group them into four categories of four.
The four category names, easiest to hardest. No words revealed yet.
Theme name plus one word from each category.
COPYCAT, MIME, MOCKINGBIRD, and T-1000 (from Terminator 2) all impersonate or imitate other things — the T-1000 literally shapeshifts into people
LOOKING GLASS (mirror), SPECTACLES (glasses), TALKIE (movie with sound), and WATER CLOSET (toilet) are all antiquated terms for things we still use today
BILLY GOAT (Billy), DAN DAN NOODLES (Dan), RICH TEXT (Rich), and TOM-TOM (Tom) all start with nicknames — short forms of William, Daniel, Richard, and Thomas
COURT JESTER (court), DIAMOND RING (diamond = baseball field), FIELD MOUSE (field), and TRACK RECORD (track) all begin with a word that names a sports venue or playing surface