granny flat 
noun informal, chiefly British
A part of a house made into self-contained accommodation suitable for an elderly relative.He said the delay on the application, to build a roof extension and granny flat on a house in York, is the longest he has ever known....
- He and his wife, who died last year, lived in a granny flat at the property.
- The castle also comes complete with a granny flat and a two-bedroomed lodge.
- Fourdrinier machine
- four-engined
- Fourex
- four-eyed
- four-eyed fish
- four-eyes
- four flush
- four-flusher
- fourfold
- four-four time
- four freedoms
- four-handed
- four hundred
- Fourier analysis
- Fourierism
- Fourierist
- Fourier, Joseph
- Fourier series
- Fourier transform
- four-in-hand
- four-leaf clover
- four-leaved clover
- four-legged friend
- four-letter word
- four noble truths