Ahau, also written Ajaw, is Ajpu in K'iche', and it closes the twenty. The Yucatec name means lord, and it is the ordinary Classic Maya word for a ruler, appearing in royal titles throughout the inscriptions; the K'iche' Ajpu means blowgunner and is the name of one of the Hero Twins of the Popol Vuh. The sign also carries the sun and the flower.
Central Mexico agrees with the flower reading, placing Xochitl in twentieth position. Between lord, sun, flower and blowgunner the sign accumulates more distinct glosses than any other in the list, which suits its position as the completion of the sequence.
Ahau has a structural prominence beyond the 260-day count. Every Long Count period ending falls on a day Ahau, because 360 and 7,200 and 144,000 are all divisible by twenty, so the great period endings that Classic monuments were raised to commemorate are always described by a number and Ahau. That is why the day appears so often on carved stelae. Ahau is not a Year Bearer in either Maya set, the Classic Ik, Manik, Eb and Kaban or the Yucatec Kan, Muluc, Ix and Kawak.
Because period endings fall on Ahau, the day is also the anchor of the Long Count's public face. A stela commemorating the close of a katun states the day as a number and Ahau together with the Haab position, and the great majority of dated Classic monuments that survive are of this kind. The twentieth sign is therefore the one a reader of the inscriptions meets most often.