Extension

How to spell extension

9 letters · 3 syllables

How to pronounce extension

Say the part in capitals loudest.

What does extension mean?

1. nounAn additional part, period, or section that lengthens or expands something, or a secondary telephone line within an organisation.

Extension in a sentence

• The builders are quoting for a two-storey extension at the back of the house.

• She asked her tutor for a one-week extension on the essay deadline.

Where does extension come from?

Language of origin: Latin

This word descends from the Latin extensio, a noun meaning 'a stretching out', which was built on the verb extendere. That verb combined the prefix ex-, meaning 'out', with tendere, meaning 'to stretch', so the literal idea was of something pulled or reached outward. English took it in during the late 1300s, by way of Old French and directly from Latin, first in senses connected with stretching and expanse and later in the everyday meanings of an added part, an extra span of time, or a telephone line. The same tendere root quietly powers a whole family of relatives, including 'tense', 'tendon', 'extend', and 'tension'. That kinship is the key to the spelling: because the base is 'extend' and 'tension', the ending is -sion rather than the -tion that trips so many writers into the wrong 'extention'.

How the word is built

• ex- (out)
• tens (stretched, from Latin tendere 'to stretch')
• -ion (noun-forming suffix)