by a hair

by a hair

By an extremely short or slim margin (of distance, time, or another measure). They're just about to close the gates! It looks like we made the flight by a hair. The race was neck and neck till the very end, but Sally won it by a hair.
See also: by, hair
Farlex Dictionary of Idioms.

by a hair('s breadth)

 and by a whisker
Fig. just barely; by a very small distance. I just missed getting on the plane by a hair's breadth. I made it onto the last flight by a hair!
See also: by, hair
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.

by a hair

Also, by a hairbreadth or whisker . Very narrowly. For example, His serve was out by a hair, or We made our flight by a hairbreadth, or Dad missed hitting the pole by a whisker. The first two hyperboles for the very narrowest margin date from the 1300s and 1400s respectively; whisker meaning "a small amount" was first recorded in 1913. Also see by the skin of one's teeth; hang by a hair.
See also: by, hair
The American Heritage® Dictionary of Idioms by Christine Ammer.
See also:
  • by a nose
  • by a whisker
  • do something by a whisker
  • by an eyelash
  • by a short head
  • win, lose, etc. by a short head
  • by a neck
  • neck and neck
  • take the checkered flag
  • take the chequered flag
References in periodicals archive
I have to give the nod to Hospital A by a hair, primarily because of those nice nurse assistants.