固
コ, かた.める, かた.まる, かた.まり, かた.い

harden, set, clot, curdle

JLPT2 G4 S8 F750

古# hard; dried out + 囗 circular enclosure → harden about an object → *hard/harden*; *stiff/stiffen* → *resolute*; *stubborn*. Other extended meanings include *tight*, *firm*, *rigid*, *strict*, *solid*, *jell*, *fortify*, *collect*, *settle*, and *settle down*.

[Full Kanji Etymology List]