insufficiency, lack, shortage
歉 centers on a state of not having enough: insufficiency, lack, or shortage of something needed.
歉 combines 兼 (concurrently, combine) with 欠 (lack, yawn), suggesting a combined lack or insufficiency. The exact historical development is uncertain, but the component relationship is plausible.
The left side 兼 suggests holding multiple things at once, and the right side 欠 means lack. Picture trying to juggle too many tasks but always coming up short—there is a constant insufficiency.
For ケン, imagine a ken (a traditional Japanese unit of length) that is too short to measure what you need, highlighting the shortage: ken -> ケン.
poor crops; famine