How do vowel patterns change the meaning of Arabic words?

In Arabic, as in other Semitic languages, words are typically formed by interweaving a root—a set of consonants that provides the core semantic meaning—with a pattern of vowels that assigns grammatical meaning.123

Vowel patterns change the meaning of words by indicating specific grammatical contexts, such as tense, voice, or part of speech. For example, using the root $\sqrt{ktb}$ (associated with the notion of writing):12

• Tense and Voice: The pattern -a-a- creates the past active stem katab- (e.g., katab-tu, "I wrote"), while the pattern -u-i- creates the past passive stem kutib- (e.g., kutib-a, "it was written").14
• Part of Speech: The pattern -i-ā- combined with the root $\sqrt{ktb}$ results in kitāb ("book"), whereas the pattern -ā-i- results in kātib ("one who writes" or "clerk").3
• Diminutives: In some nominal stems, specific vowel patterns can alter the noun's nuance, such as the -u-ay- pattern in kulayb- ("little dog") derived from kalb ("dog").1

This system allows the same root to generate a wide array of related terms by simply shifting the vocalic structure.12