| Definition -
The study of how words have altered their meaning over time.
As an example, the following lists the Oxford English Dictionary's series of entries for Santa Claus from the term's first written appearance in English in 1773 to 1850:
1773 N.Y. Gaz. 26 Dec. 3/1 — "Last Monday the Anniversary of St. Nicholas, otherwise called St. A Claus, was celebrated at Protestant-Hall."
1808 Salmagundi 25 Jan. 407 — "The noted St. Nicholas, vulgarly called Santaclaus— of all the saints in the kalendar the most venerated by true hollanders, and their unsophisticated descendants."
1821 Weekly Visitor IV. 262/1 — "For time immemorial the Dutch had a tradition, that there existed a being of no earthly birth, who was called Santa Claus."
1828 Longfellow in Life (1891) I. 152 — "Gew-gaws for the Bifana, who acts here the same comedy for children that Santiclaus does in America."
1850 Susan Warner Wide Wide World xxviii — "I used to think that Santa Claus came down the chimney."