adjective
passing
PAS-ing/pˈæsɪŋ/
Lasting only a short time.
A passing rain shower leaves a puddle in the park.

Etymology
Something passing is going by rather than staying, which gives the sense of temporary or brief. The same image suggests attention given casually, as though while moving past.
In context
not a brief glance I beg a passing word but as thou dwellest with thy disciples Lord familiar condescending patient free come not to sojourn but abide with me
More examples
- The new style turns out to be a passing fad.
- She dismisses the worry as a passing feeling.
- His passing enthusiasm fades after a week.
Forms
passing
pass verb — To move past a particular point.