stubborn

thighbone; patella

firm, resolute / honest, steadfast / stern, strict, serious / safe / indestructible, unwreckable

hard / tight / strong; firm / strict / inflexible

(Christianity) choir

love that is one-sided, unreturned, unanswered, unrequited, unreciprocated, etc.; unrequited love; crush

(cooking) potato starch

Qatar (a country in the Middle East)

katal (in the International System of Units, the derived unit of catalytic activity; one mole per second)

Keeping a material's shape that does not crack or break apart; hard / Keeping one's appearance or facial expression; serious