He is Gríma, son of Gálmód. Wormtongue is just a nickname.
The keyword bit is actually "Gríma", which apparently derives from the Icelandic word meaning "mask".
Most of the characters do have "keywords" as MrSalmon puts it:
Frodo: from Old English fród meaning 'wise by experience'.
Sauron: originates from the adjective saura "foul, putrid" in Tolkien's invented language Quenya.
Gandalf: he Old Norse name Gandalfr incorporates the words gandr meaning "wand", "staff" or (especially in compounds) "magic" and alfr meaning "elf" or in a wider sense "(mythological) being"
Saruman: "man of skill" in the Mercian dialect of Anglo-Saxon
and so on. (all from Wiki)