bifocals

From bi- + focal (see focus), coined in 1824 by John Isaac Hawkins, inventor of trifocals. When the concept of bifocals was originally conceived by Benjamin Franklin, he called them double spectacles.

bifocals pl (plural only)

1. Spectacles that have corrective lenses of two different powers; used by people who need both distance and reading glasses.
   • 2002, Zadie Smith, The Autograph Man, Penguin Books (2003), page 116:

     He unfolded a pair of bifocals and thrust them as far up the bridge of his nose as possible.

• bifocal
• multifocals
• trifocals