Meanings

second nature

awkwardness experienced on subsequent encounters with someone (despite a smooth first encounter)

double glazing

two prices (for the same product)

mercury(II) chloride

double

disulfide

to take off one's hat to a person

stealing second base

second child

pair of gods (esp. Izanagi and Izanami)

managing data from two locations

motorcycle (with a displacement of 50cc or more)

diploidy

disulfuric acid

diphosphoric acid

dithionic acid

peroxodisulfuric acid

double hane (move)

dibasic acid