Appendix:English words where C is pronounced exceptionally

The following English words contain the letter "c" pronounced in a way which is an exception to the rule described as Hard and soft C: the soft "c" occurs when the "c" comes before the letters "e", "i" or "y", and the hard "c" occurs elsewhere.

Hard c where soft c expected

• arc ~ed, ~ing
• Celt ~ic, ~s (by one pronunciation)
• Cenozoic (by one pronunciation)
• Cillian
• ecce (by one pronunciation)
• foci (by one pronunciation)
• loci (by one British pronunciation)
• pescetarian
• Quebecer ~s
• recce ~d, ~ed, ~ing, ~s
• sceptic (first occurence)
• soccer
• supercalifragilisticexpialidocious (second occurrence)
• synced, syncing
• cyattie

Also, in any personal name beginning with the patronymic prefix Mc or Mac, the c is always hard, even if the name continues with e, i or y. (In Macy, the Mac- is not a patronymic prefix, and the c is soft.)

Soft c where hard c expected

• acai, ~s. Should be spelled açaí.
• caecilian, ~s
• Caelum
• Caesar, ~ean, ~eans, ~s
• Caesarea
• caesium
• caetera
• coelacanth (first occurrence), ~s
• coeliac (first occurrence)
• corpuscle (second occurrence), ~s
• crepuscle, ~s
• facade, ~s. Should be spelled façade.
• lac (etymology 4), ~s
• limacon, ~s
• muscle, ~d, ~s, muscl~ ~ier, ~iest, ~ing, ~y. (Silent <c>, actually.)
• Percabeth (derived from "Percy").
• septicaemia
• soc ~s (etymology 1)

In many Latin loanwords, "ae" and "oe" are a single vowel resembling "e", and most such words are pronounced with a "soft" sound. This does not apply to all "cae" or "coe" words; in Caerleon and coefficient, the starting "C" makes the "hard" sound as would be expected.