From the Semitic root و-ل-د (w-l-d), relating to birth and offspring. This root is extraordinarily productive in Arabic: it yields وَلَد (walad, "boy/child"), وَالِد (wālid, "father"), وَالِدَة (wālidah, "mother"), مَوْلُود (mawlūd, "newborn"), مَوْلِد (mawlid, "birthplace" or "birthday"), and even مَيْلاد (mīlād, "birth/nativity"), the word used for Christmas. The root appears in cognate form in Hebrew ילד (yeled, child) and Aramaic.

In Arabic-speaking cultures, the birth of a child is traditionally announced with the phrase "مَبْرُوك المَوْلُود!" (Mabrūk al-mawlūd! — "Congratulations on the newborn!"). The Prophet Muhammad's birthday, celebrated across much of the Muslim world, is called المَوْلِد النَّبَوِي (Al-Mawlid al-Nabawi), directly from this same root. Be careful not to confuse وَلَدَ (walada, "to give birth") with وَلَد (walad, "boy/son") — same root, different part of speech, and beginners often mix them up.