noun
quirk
KWURK/kwɜːrk/
An unusual feature or deviation from expectation.
This carrot has a quirk: its root curls like a corkscrew.

Etymology
Its origin is unknown. Early uses meant “a quibble” or “an artful evasion”; the later sense “peculiarity” underlies today's odd habit or feature.
In context
so in a quirk of etymological History the benign English word Fascination derives from the evil eye
More examples
- One of her quirks is naming every houseplant.
- A quirk in the software makes empty folders appear twice.
- By a quirk of fate, we became neighbors again.
Forms
quirk · quirks
quirky adjective — Having unusual or distinctive traits.
Similar words
- peculiarity
- Emphasizes a distinctive trait rather than an unexpected event.
- oddity
- Often names a whole strange thing, not just one feature.
- twist
- Fits an unexpected turn of events rather than a habitual trait.