bifocal
UK[ˌbaɪˈfəʊkl̩]US[ˌbaɪˈfoʊkl̩]
adj
Having two different focal lengths, especially relating to a pair of eyeglasses with lenses that correct for both near and distant vision.
n
(bifocals) A pair of eyeglasses with bifocal lenses.
Morpheme Breakdown
bi
focal
bi
two
focal
relating to a focus
Etymology
The word 'bifocal' is a modern scientific compound, coined in the 19th century. Its first element, 'bi-', is a productive Latin-derived prefix meaning 'two'. The second element, 'focal', originates from the Latin 'focus', which initially meant 'hearth' or 'fireplace'—the central gathering point of a home. This meaning was abstracted in scientific Latin to denote a central point of convergence, particularly for light or mathematical attention. Therefore, 'bifocal' literally means 'having two focal points', a logical and descriptive term for lenses designed to bring two different distances (near and far) into clear focus for the wearer.
Analysis
Structure: bi (two) + focal (relating to a focus)
- bi: A combining form from Latin 'bis', meaning 'twice' or 'two'. It functions as a prefix indicating two parts or aspects.
- focal: An adjective derived from the Latin word 'focus' (hearth, fireplace), which in modern scientific use came to mean a point where rays converge. The suffix '-al' indicates 'relating to'.
Examples
He switched to bifocal lenses to read without needing separate glasses.
The invention of bifocals is popularly attributed to Benjamin Franklin.
These new bifocals have a seamless line between the two vision zones.