The Root System

Every Hebrew speaker already owns the single most important key to Arabic: the שורש. Both languages build almost their entire vocabulary from three-consonant roots poured into fixed patterns. The machinery you absorbed in school — finding the שורש, recognizing the משקל — is not merely similar to Arabic's system. It is the same system, inherited from the same ancestor language.

One root, a whole family

Take the root כ.ת.ב — writing. Arabic has precisely the same root, ك-ت-ب, with the same three consonants in the same order (Arabic ك is Hebrew כ, ت is ת, ب is ב). Watch what each language grows from it:

Roots + patterns = words

A root supplies the idea; a pattern supplies the grammar — doer, place, product, action. Hebrew calls patterns משקלים, 'weights'. Arabic calls them أَوْزَان (awzān) — the plural of وَزْن (wazn), which means... 'weight'. The two grammatical traditions even chose the same metaphor. Here is one pattern doing identical work in both languages: ma + root = the place where the root happens (Hebrew מִפְעָל/מִקְדָּשׁ-type nouns).

Every row is a real correspondence. Arabic دَرَسَ (darasa, 'he studied') is Hebrew דָּרַשׁ with the classic ס↔ש sound shift — a מִדְרָשָׁה and a مَدْرَسَة are both houses of study. Hebrew טַבָּח (cook) and מִטְבָּח sit on the same ט-ב-ח that gives Arabic its kitchen. And מִסְגָּד is Modern Hebrew borrowing مَسْجِد right back — the place of סְגִידָה, bowing (Biblical סָגַד), which is exactly what سَجَدَ means.

How to extract a root

The drill is the one you know from Hebrew class. Peel off the definite article الـ; peel off pattern prefixes — مُـ, مَـ, تَـ, اِسْتَـ, نَـ; ignore the long vowels ا و ي that patterns insert; drop a final ة. Whatever three consonants remain are the root. This matters practically: serious Arabic dictionaries (like classical Hebrew ones) are organized by root, so مَكْتَبَة is listed under ك-ت-ب, not under م.