熟字

熟字	shú zì	familiar words / known Chinese character
熟	shú	ripe; mature / thoroughly cooked; done / familiar; acquainted / experienced; skilled / (of sleep etc) deep; profound / also pr. [shou2]
字	zì	letter / symbol / character / word / CL:个 / courtesy or style name traditionally given to males aged 20 in dynastic China