could you show me englishgramar
Its the word of course. You need words for sentences.
Without the whole sentence, it's not always possible to understand the meaning. Take the word "lighter" as an example. Does this mean a cigarette lighter, or does it refer to an object that is not as heavy as another? Or a room with a bigger window than the last?
"you need word for sentences"...ya, and don't you need character for words? so this is the basic unit?
words can have meaning as parts of a sentence. some words dont have meaning like at, of , etc. But sentences as they convey a message on communication with others, can be the basic unit of meaning. However, it is reasonable to think that both words and sentences as the basic umits of meaning.
A sentence fulfills all six functions of language (Jakobson). A single word does not.
Neither, it*s the morpheme.
It's not the morpheme because some morphemes have no meaning on their own. The word dog is a word and a morpheme but the word dogs has two morphemes, dog and s. s has no meaning on its own. Therefore the smallest unit of meaning is the word.