Ok, so before we start learning Arabic, we need to know an introductory point. A word can be analysed in two ways. Sometimes, we analyse a word on its own regardless of any other words and some other times, we analyse a word in a sentence and its relation with other words.
To make this clear: think of John. We can study John’s life in two ways (at least). We can think of John as an individual and study his career, his education, his sense of fashion. Or we can think of John as a member of a family and study his role in the family i.e. he is a husband, a father, an uncle etc.
In the same way, words are either studied on their own or as a member of a sentence. I hope the following example makes this clear. Think of the word عالم. Right now, it is not in any sentence. It’s on its own and lonely.
Morphology
Let’s see what are some of the things we can say about عالم as it is:
We know it comes from root ع – ل – م the same room from which علم (knowledge) is made. So its meaning has something to do with knowledge.
We also know its wazn is فاعل. That tells us this word is not a verb (فعل). Because فاعل is a wazn that only a noun (اسم) can have. That also tells us that عالم should be the doer/possessor of the root. In our case since the root is knowledge so possessor of knowledge, knowledgable.
We can also change it slightly to get a new meaning. For example if we add ان to عالم it becomes عالمان which is a new word and it means two scholars:
عالم + ان = عالمان
Ok, these are all things we can say about عالم on its own and out of a sentence. These are studied in Morphology or as Arabs call it علم الصرف.
Syntax
Now let’s put it into a sentence.
کتب العالمُ الکتابَ لالطالب (The scholar wrote the book for the student.)
Ok, now our word has joined some other words to form a sentence (like John joined other people to form a family). So, now عالم has new roles in this sentence. It is the doer of the action (i.e. writing). What do we call the doer of an action in Grammar? Subject. In Arabic we call it فاعل.
Now a question: Could عالم be the Subject, if it wasn’t in a sentence?
– No. Duh!
Exactly, so being a sentence gave our word new roles. What other role can عالم take in a sentence. Well, we can change the sentence slightly to make it:
کتب الطالب الکتاب لالعالم (The student wrote the book for the scholar.)
Now as you can see the عالمis no longer to the doer of the action. Rather, it is the student الطالب who has written the book and is now the Subject of the sentence or فاعل.
These new roles that a word takes in a sentence are studied in Arabic Syntax or as Arabs call it: علم النحو.