trademark (n.)

also trade-mark, 1838 (the thing itself attested continuously from 14c., apparently originally the watermarks on paper), from trade (n.) + mark (n.1) in a specialized sense of "stamp, seal, brand, etc. placed upon an article top indicate ownership or origin" (mid-13c.). Figurative use by 1869. As a verb, from 1904. Related: Trademarked; trademarking. This sense of mark also yielded the meaning "particular brand or make of an article" (1660s), hence its use in 20c. names of cars, etc., Mark I, Mark II, etc.