Originally odd jackets were suit jackets worn with different pants outside the workplace. Later on they were made as freestanding jackets without trousers of the same bale of material.
Mainly for leisure, the outdoors in Tweed and Flannel.
Ref.: The Rake, vol 59 p. 153ff. [145/5007]
Odd jackets with their more casual touch work well with knitted neckties.