Definitions of Grammar

Syntax
The grammatical arrangement of words in a sentence is called syntax.
Example
I like to eat apples.

Word
Arrangement of letters that produces a perfect meaning is called a word.
Example
Eat, Drink

Syllable
Division of a word in small units while pronouncing it, is called a syllable.
i. Monosyllable (one unit)
A word that is pronounced with the single jerk of the tongue.      e,g  small, full
ii. Disyllable (two units)
A word that is pronounced with the two jerks of the tongue.         e,g   deport
iii. Polysyllable  ( more than two units)
A word that is pronounced with more than two jerks of the tongue.   e,g     intelligent

Phrase
A group of words that makes some sense but does not give a complete sense is called a Phrase.
Example             in the morning,    over the sky