Not normal; odd, unusual, surprising, out of the ordinary.
Outside of one's current relationship; unfamiliar.
Having the quantum mechanical property of strangeness.
Not belonging to one.
Unfamiliar, not yet part of one's experience.
Of an attractor: having a fractal structure.
Sex outside of one's current relationship.
Out of the ordinary
Not adhering to convention or accepted standards
Atypical
Something or someone that is unconventional.