ETYMOLOGY
from Middle English belsyre,
from belfair (beautiful) (from Old French)
EXAMPLE
“… With those delicious Brooks, by whose immortall streames
Her greatnesse is begunne: so that our Riuers King,
When he his long Descent shall from his Bel-sires bring,
Must needs (Great Pastures Prince) deriue his stem by thee,
From kingly Cotswolds selfe, sprung of the third degree: …”
From: Poly-Olbion
By Michael Drayton, 1612
Lexicophilia 