Uncustomary (adjective)

Not in accordance with or established by custom; not usual or typical.

Origin:

From un- (not) + customary (usual).

Examples:

1. It was deemed uncustomary for women to wear pants in the early 1900s.
2. The waiter's behavior was uncustomary as he was not following the usual protocols.
3. It is uncustomary for the company to allow employees to work from home.
4. The use of a fork and knife to eat pizza is uncustomary in Italy.
5. The uncustomary cold weather this summer has caused many problems for farmers.