This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
歖 is a rare character combining 喜 (joy) and 欠 (open mouth, related to breath or expression). The exact historical development is uncertain, but it likely expressed a joyful exclamation or sound.
The left side 喜 means joy, and the right side 欠 often relates to an open mouth or breath. Picture a joyful person with an open mouth, perhaps laughing or cheering, but the exact meaning is unclear.
For キ, imagine a key unlocking a joyful expression: key -> キ, and the open mouth 欠 beside 喜 suggests a happy sound.
—