co-worker
鵷 is a rare kanji whose standalone meaning is unclear. The given gloss "co-worker" is likely a specialized or historical usage, but the character does not have a well-established independent meaning in modern Japanese.
鵷 combines 宛 (possibly phonetic) with 鳥 (bird). The exact historical origin and the connection to "co-worker" are uncertain.
The left side 宛 can suggest a bent person, and the right side 鳥 is a bird. Imagine a bird working alongside a person as a co-worker, though this is a stretch.
For エン, picture a bird ending its workday with a co-worker: end -> エン, and the bird flies off together.
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mythical Chinese bird similar to the Chinese phoenix