6-letter words with C as the 4th letter and U as the 5th letter

The frame is _ _ _ C U _, so C and U take the middle two slots. RESCUE, CIRCUS, CAUCUS, and CONCUR are the familiar entries, and a run of -US, -CUP, and -CUS spellings carries most of the group. Only four of the words count as common, and EXACUM at 17 tops the scores.

The _ _ _ C U _ frame

• 35 tournament words fit the frame _ _ _ C U _.
• Fifteen close on -US, among them ABACUS, CAUCUS, CIRCUS, and JUNCUS.
• Six end in CUP: EGGCUP, EYECUP, GILCUP, HICCUP, OILCUP, and TEACUP.
• EXACUM leads at 17; HICCUP and JUNCUS reach 15.
• C opens 8 words, the most of any first letter.
• No five- or seven-letter group carries C fourth and U fifth.

The -US and -CUP families

Fifteen of the 35 words end in -US, a tidy Latin tail covering ABACUS, CAUCUS, CIRCUS, DISCUS, and JUNCUS. Several stack it onto the C as well: CAUCUS, CIRCUS, and CUSCUS all close on the full -CUS. It is the single strongest clue in the set.

Six more are CUP compounds: EGGCUP, EYECUP, GILCUP, HICCUP, OILCUP, and TEACUP. That group is unusually plain for a tournament list, since each word simply names an object.

Scores and the missing neighbours

EXACUM is the runaway leader at 17, driven by its X. HICCUP and JUNCUS follow on 15, OFFCUT takes 14 on a doubled F, and EYECUP, VISCUM, and CAECUM land on 13, 13, and 12. FESCUE shows the softer spellings still reach 11.

The shape belongs to six letters alone. Five- and seven-letter words with C fourth and U fifth do not share it, so there is no shorter or longer list to check against. C opens eight of the words, the largest group, and the rest scatter across the alphabet.