From the root ك-ل-م (k-l-m), connected to the verb كَلَّمَ (kallama, "to speak to"). This tri-literal root is one of the most productive in Arabic, also giving كَلَام (kalām, "speech/talk") and the verb يَتَكَلَّم (yatakallam, "he speaks"). Cognate with Hebrew מִלָּה (millá, "word"), reflecting their shared Semitic ancestry.

In Islamic tradition, the phrase كَلِمَة التَّوحِيد (kalimat at-tawhīd) — "There is no god but God" — is considered the most important single utterance a Muslim can say, showing how deeply Arabic culture prizes the weight of individual words. The root also lives in the title "Mutakallimūn," the classical Islamic theologians who debated the nature of divine speech.