古
コ, ふる.い, ふる, ふる.す, ふゆ

old

JLPT4 G2 S5 F509

The relevant oracle bone form of 古 combines 口 mouth + an object filling it → expectorate *old*, *dried out*, *hard* food → *dry up*; *stale* → *used*; *old-fashioned*.

[Full Kanji Etymology List]