Word, vocable, term can mean a letter or combination of letters or a sound or combination of sounds capable of being pronounced and expressing an idea that is by tradition or common consent associated with the letters or the sounds.
Word applies to a letter or combination of letters or a sound or a combination of sounds that forms an indivisible whole constituting one of the ultimate units of a language.
Vocable throws emphasis upon a word as pronounced or spelled rather than as a unit of meaning.
Term applies both to words and to phrases that express a whole idea and form one of the units of expression in a language, applying especially to units with a more or less precise technical use or meaning.