Theatre or theater - which word is correct for using in GB and US? I faced with both and also heard the opinion that "theatre" is not used in US, although it's definitely not true.
Dictionaries say that "theater" is US spelling while "theatre" is UK spelling. However, according to some dictionaries "theatre" is now equally acceptable in the US.
The Oxford English Dictionary (OED) says the “The earliest recorded English forms, c1380, are theatre and teatre; from c1550 to 1700, or later, the prevalent spelling was theater (so in Dictionaries from Cawdrey to Kersey), but theatre in Holland, Milton, Fuller, Dryden, Addison, Pope; Bailey 1721 has both, ‘Theatre, Theater’: and between 1720 and 1750, theater was dropped in Britain, but has been retained or (?) revived in U.S.”
- According to the British National Corpus the word theatre is more common in the UK.
- According to the Corpus of Contemporary American English the word theater is more common in the US.
In British English, some words from French, Latin or Greek end with a consonant followed by an unstressed -re (pronounced (non-rhotic accent) /ə(ɹ)/ or (rhotic accent) /ɚ/). In American English, most of these words have the ending -er. The difference is most common for words ending -bre or -tre: British spellings calibre, centre, fibre, goitre, litre, lustre, manoeuvre, meagre, metre, mitre, nitre, ochre, reconnoitre, sabre, saltpetre, sepulchre, sombre, spectre, theatre (see exceptions) and titre all have -er in American spelling.
In the US it's also common among some folks to refer to the building as "theater" and to the act as "theatre". However, not everyone follows such practice, and many exclusively use the American spelling. "Theatre" often appears in the proper names of American theaters, for example: the American Ballet Theatre, the Muncie Civic Theatre, and the Genessee Theatre. When referring to these buildings by the common noun "theater" is the usual spelling.