By ὀνοματοποιια the Greek grammarians understood that principle, or tendency in the growth of language, according to which certain words are formed by an imitation of the sounds which they signify. Thus, ὀγχ, the root of the Greek word ὀγχᾶσθαι, to bray, may be considered to have been formed of a human mimicry of that animal to which human beings of the lowest cerebral capacity are peculiarly compared; and in the same way, laogh, the Gaelic for a calf, seems to contain a sound to which only the throats of Highland calves, Highland chieftains, and Highland crofters are competent. The word onomatopœia, like some other technical terms of the old grammarians, is not particularly happy, for it means only and generally word-making, or rather name-making, and says nothing of the principle by which the special class of words in question is made. Instead of this term, therefore, I should prefer to speak of the imitative or pictorial principle in the formation of human speech; and I should contrast the whole class of words in which the operation of this principle can be traced, with another class, derived from ideas or notions about the thing to be named in the mind of the word-maker. Thus, the modern Greeks call a cock πετεινό, that is, the fowl, or flying animal, from πέτομαι, to fly; and the Latin word, equus, a horse, if it comes, as Professor Müuller says, from the Sanscrit root â'su, swift, will be another word formed on the same principle. The roots of these words I propose to call notional roots, as contrasted with the onomatopoetic class of roots, which I propose to call pictorial roots, or roots formed by phonic imitation.