Motivation explains the relationship between the linguistic symbol and its meaning,or the
logical reason why a certain word has a certain meaning.
As mentioned earlier,the relationship between sound and meaning is arbitrary and
conventional.Motivation seems to contradict the theory.The answer is "yes and no".By "yes",we mean all the mono-morphemic words in a language are non-motivated except a few onomatopoeic words which imitate the natural sounds or noises.By "no",we mean many multi-morphemic words are motivated,for in many causes the meaning of the whole word is the combination of the morphemes.The morphemic structure explains the meaning.