thru

thru — preposition

1. used in informal US writing as a shorter form of 'through', to show movement fro

1.prepositionB1
Definition

used in informal US writing as a shorter form of 'through', to show movement from one side or end to the other, or to indicate a period that lasts up to and including a particular date or time.

Example

Eitan drove thru the tunnel to reach the other side of the mountain.

spatial: from one side to the other

The library is open Monday thru Friday from nine to six.

temporal: up to and including [days]

Common collocations
  • drive thru
  • go thru
  • come thru
  • flip thru
  • read thru
  • Monday thru Friday
  • thru the night
Synonyms
  • through

    standard spelling; use in all formal and most neutral contexts

Grammar Patterns

thru + noun phrase (spatial)

thru + time period (temporal)

Usage Note

Only used in informal American English — common on road signs, in notes, text messages, and casual correspondence. In academic essays, business letters, or any formal context, use 'through' instead. Also appears in fixed compounds such as 'drive-thru' and 'thru-way'.

Common Mistakes

The train passes thru the station every hour.' (in a formal essay).
The train passes through the station every hour.
'thru' is too informal for academic or professional writing.
She walked thru the park' (in British English).
She walked through the park.
'thru' is very rare in British English; always use 'through'.

Word family

Synonym discussion

Sense: preposition/1

'Thru' and 'through' share the same meaning and grammatical function. The difference is purely register and spelling: 'thru' is an informal US abbreviation used in signs, notes, and casual writing, while 'through' is the standard spelling appropriate in every context. 'Via' is narrower — it means 'by way of' and is used for routes or means of transmission ('fly via London', 'send it via email'), whereas 'thru/through' can also express duration ('Monday through Friday') or completion ('read through the report'). Use 'through' for all formal needs; reserve 'thru' for signs and quick notes.

thru ↗through ↗via ↗

Common collocations

Phrases

  • drive-thru
  • go thru
  • come thru
  • flip thru
  • read thru
  • Monday thru Friday
  • thru the night

Etymology

Old EnglishMiddle EnglishAmerican English

'Thru' is a phonetic simplification of 'through' that appeared in American English during the 19th-century spelling-reform movement, which sought to make English spelling match pronunciation more closely. While the reform movement did not succeed broadly, 'thru' gained wide public recognition through its use on road signs (especially 'drive-thru') and in informal writing. Today it remains a marker of casual American usage.