Qaph is the nineteenth letter of the Syriac abjad and the first of the hundreds, with the numeral value one hundred. It writes a voiceless uvular stop, made further back in the mouth than k, at the very rear. It joins on both sides.
Its name is the inherited Northwest Semitic word usually glossed as the back of the head. The gloss belongs to the older linear alphabet and describes nothing in any Syriac hand.
Qaph is one of the letters the language sets against a plainer counterpart, standing to kaph roughly as sadhe stands to semkath and teth to taw. The contrast is real in the classical reading and it separates roots, so a word takes qaph or it takes kaph and the choice is not open.
The four letters that close the alphabet, qaph, rish, shin and taw, carry one hundred, two hundred, three hundred and four hundred between them, so all the higher figures fall at the end of the sequence. That makes qaph the letter a scribe reaches for whenever a number passes ninety-nine, and it is the reason the last four letters of the Syriac alphabet turn up so often in the margins and the quire signatures of manuscripts, where they are doing arithmetic rather than spelling anything.
Because qaph joins on both sides it never forces a break in a word, unlike the eight letters that join only to the right, so a figure written with qaph sits inside a connected run rather than standing apart from one. The uvular articulation is maintained in the classical reading and varies among the modern spoken descendants of Syriac, as the pharyngeals do, so how the letter sounds today depends on who is reading it.