hob‧by‧horse /ˈhɒbihɔːs $ ˈhɑːbihɔːrs/ noun [countable]
[Date: 1500-1600; Origin: hobby 'small horse' (14-19 centuries) (probably from Hobbin, a man's name, from Robin) + horse]

1. a subject that someone has strong opinions about and that they talk about too much:
I’m afraid safe driving isn’t Jaqui’s only hobbyhorse.
be on your hobbyhorse
Vicky was on her hobbyhorse again.

2. an old-fashioned toy made of a horse’s head on a stick

[TahlilGaran] Dictionary of Contemporary English ▲