STERN is validvalid

unyielding [adj STERNER, STERNEST] : STERNLY [adv], STERNNESS [n] / the rear part of a ship [n STERNS]

13,265 of 196,601 in NWL2023·also valid in CSW24

severe [adj STERNER, STERNEST, STERNLY] / to back, row backwards, also STARN [v -ED, -ING, -S]