single file, in

single file, in idiom
Also, in Indian file. Aligned one behind the other, as in We have to bike in single file here, or The children were told to march in Indian file. Both usages are associated with military formations; the first term was first recorded in 1670; the variant, alluding to the usual marching order of Native Americans, was first recorded in 1758.

The American Heritage® Dictionary of Idioms by Christine Ammer. Copyright © 2003, 1997 by The Christine Ammer 1992 Trust. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

Comments
Improve this definition.
Do you have more to add? Share your linguistic knowledge or observation.
/Register to save your comments.