anagram (n.) Look up anagram at Dictionary.com
transposition of letters in a word so as to form another, 1580s, from French anagramme or Modern Latin anagramma (16c.), both from Greek anagrammatizein "transpose letters," from ana- "up, back" (see ana-) + gramma (genitive grammatos) "letter" (see grammar). Related: Anagrammatical; anagrammatically.