In British usage, some words of French, Latin, or Greek origin end with a consonant followed by -re, with the -re unstressed and pronounced /ə(ɹ)/. Most of these words have the ending -er in the US. The difference is most common for words ending -bre or -tre: British spellings theatre, goitre, litre, lustre, mitre, nitre, reconnoitre, saltpetre, spectre, centre, titre; calibre, fibre, sabre, and sombre all have -er in American spelling. The ending -cre, as in acre, lucre, massacre, mediocre, is preserved in American English, to indicate the c is pronounced /k/ rather than /s/. After other consonants, there are not many -re endings even in British English: louvre, manoeuvre after -v-; meagre, ogre after -g-; euchre, ochre, sepulchre after -ch-. In the US, ogre and euchre are standard; manoeuvre and sepulchre are usually maneuver and sepulcher; and the other -re forms listed are variants of the equivalent -er form.
