The traditional RP pronunciation of the architectural noun clerestory reflects its supposed origin - 'CLEAR-story', IPA: /'klɪər ,stɔː rɪ/. A pronunciation with four syllables, in which the first two vowels are similar to that in 'get', seems to be gaining ground, ('cle-REST-er-y', /klɛ 'rɛ stə rɪ/).
- A clerestory is a band of windows running round a building (originally, after the classical period, always a church) below the level of the main roof but above all subsidiary roofs, arches etc, to admit light to the building. In modern times, it has been applied to rows of small windows above the normal roof line, as in camper vans and railway carriages, made to admit more light than commonly available in such structures without them.
- Etymological note: OED makes it clear that no definite derivation has been established, but that the "assumed derivation" from 'clear', meaning 'lighted', and 'storey', a level of a building, is commonly believed. AWE would add that it remains a good guide and mnemonic to both the meaning and the pronunciation.