How many words can you think of that end in -onym? Antonym and synonym are two. Antonyms are words with opposite meanings. Synonyms are words that mean the same thing. The ending, or suffix, comes from the Greek word onyma, which means “name.” Words that end in -onym are names for a type of word.

Acronym

A word or name formed by combining the first letters or groups of letters from a phrase. For example, SCUBA comes from self-contained underwaterbreathing apparatus.

Aptronym

A name that's especially suited to the profession of its owner. For example, Sally Ride, the astronaut.

Capitonym

A word that takes on a new meaning when capitalized. For example, polish (pol-ish), Polish (Polish).

Charactonym

The name of a literary character that especially suits his or her personality. For example, Charles Dickens's Scrooge is a miser.

Eponym

A real or mythical person from whose name a place, a thing, or an event is taken. The earl of Sandwich, for example, the first person to ask for meat between two slices of bread, is the eponym of the modern sandwich.

Heteronym

Two or more words with identical spelling but different meaning and pronunciation. There are so many bows. How about bow and arrow? Bow of a boat?

Homonym

Words that sound alike (and are sometimes spelled alike) but name different things. For example, die (to stop living) and dye (color).

Pseudonym

From the Greek pseud (false) and onym (name), a false name or pen name, used by an author. Mark Twain is a pseudonym for Samuel Langhorne Clemens.

Toponym

A place name or word that began as the name of a place, such as hamburger (from Hamburg, Germany) and afghan (a soft blanket from Afghanistan).