共焦

共焦	gòng jiāo	confocal (math.)
共	gòng	common / general / to share / together / total / altogether / abbr. for 共产党, Communist party
焦	Jiāo	surname Jiao
焦	jiāo	burnt / scorched / charred / worried / anxious / coke / joule (abbr. for 焦耳)