in

in — noun

1. the written short form of 'inch', a measurement of length in the imperial system

1.nounB1
Definition

the written short form of 'inch', a measurement of length in the imperial system. One inch is about 2.54 centimetres, and 12 inches make one foot.

Example

The shelf needs a gap of at least 3 in. between each plank.

collocation: number + in. + between [objects]

Christopher bought a 2½ in. paintbrush for the fence.

collocation: [size] in. + noun (tool)

Common collocations
  • 3 in.
  • in. long
  • in. wide
  • in. thick
  • per sq. in.
  • in. of rain
Synonyms
  • inch

    the full word, used in speech; 'in.' is only used in writing

Antonyms

Grammar Patterns

number + in. + noun (measurement)

in — adjective

in — adverb

in — prefix

in — preposition

in — suffix

Word family

Synonym discussion

Sense: preposition/1

The preposition 'in' is the most neutral and frequent way to express location within boundaries — used for containers, rooms, areas, and abstract spaces ('in the box', 'in London', 'in trouble'). 'Inside' adds emphasis on being fully enclosed or separated from the outside ('inside the cave', 'inside the organisation'); it often carries a sense of contrast with what is outside. 'Within' is more formal and typically used for boundaries or limits that are not necessarily physical containers ('within the city walls', 'within the rules', 'within a week'); it sounds literary or bureaucratic in everyday contexts. 'Into' focuses on movement toward the interior rather than static location: you put something into a bag, walk into a room, or look into a problem. If the focus is movement, choose 'into' or 'in' with motion verbs; if the focus is static location, choose 'in', 'inside', or 'within'. Example: 'She walked in the shop' (movement + location) vs 'She walked into the shop' (movement only) vs 'She was inside the shop' (static, enclosed).

Common collocations

Phrases

Prepositions

  • in for
  • in on
  • in with

Etymology

Proto-Indo-EuropeanProto-GermanicOld EnglishEnglish

The preposition and adverb 'in' comes from Old English 'in', which goes back to a Proto-Germanic root *in, and further to the Proto-Indo-European root *en 'inside'. It has remained remarkably stable for over a thousand years, appearing in nearly identical form across all Germanic languages (Dutch in, German in, Swedish i). The same PIE root is also the source of Latin in, Greek en, and Welsh yn. The negative prefix in- (as in 'invisible') comes from a different origin — Latin in- from PIE *ne 'not' — and was reinforced in English through French loanwords. The suffix -in (as in 'sit-in') is a modern, mid-20th-century English development, patterned on 'sit-in' from the US civil rights movement.