Part of speech: noun

Sense: a casually made remark or observation not meant to be taken seriously or given much thought.

Usage:

1. "During the meeting, Sarah made a passing comment about the weather, which lightened the mood."
2. "His passing comments about politics revealed his lack of understanding in the subject."

Part of speech: adjective

Sense: done or happening quickly, briefly, or without much attention.

Usage:

1. "Emily gave the painting only a passing glance before moving on to the next exhibit."
2. "He had a passing interest in football but was never really a fan."