Thru

Thru is an informal or nonstandard variant spelling of the word through. It is most common in American English and appears in signage, branding, and casual writing. In many contexts it signals convenience or speed, such as in commercial or service formats that move customers through a process without entering a building.

Common usages include drive-thru or drive-through, describing services designed for customers who remain in their vehicles; thru traffic, referring to vehicles moving along a route without stopping; and Thruway or Thruway branding, where Thru is used as a proper noun or part of a brand name.

Origins stem from phonetic simplification and space-saving on signs, a trend that gained prominence in the 20th century. The form is widely understood, but is generally considered nonstandard in formal writing, and most style guides prefer through in formal documents.

In contemporary writing, thru is typically avoided in academic, professional, or formal prose. Some dictionaries label it as informal or dialectal; it is acceptable in signage and marketing contexts but not in precise or scholarly contexts. When writing for formal audiences, use through unless you are reproducing a trademark, quoting a source, or referencing a brand name that uses the spelling Thru.