1.
each other, one another
Refers to a reciprocal relationship between two or more parties.
2.
mutual, reciprocal
Used adverbially to describe actions done by both parties.
COMMON PATTERNS:
- お互いに (mutually - adverbial use)
- お互い様 (we're even/mutual - set phrase used when both parties share a burden)
- お互いの〜 (each other's ~)
Note: The お prefix is standard and rarely omitted; 互い alone sounds unnatural in most contexts.
USAGE:
お互い様 is a polite expression acknowledging that both parties are equally affected or responsible. It's commonly used as a humble response to apologies or thanks.
Compare with 相互 (mutual/reciprocal), which is more formal and used in written/official contexts.