Psalm 133/Notes/Grammar.v. 1.872894
v. 1a – The definite article on הַֽמַּעֲל֗וֹת indicates the specific song of the specific ascents of the pilgrims to Jerusalem, as consistent superscriptions of the entire collection of Pss 120-134.[1] This may refer to the collection of songs performed by those returning from exile, which later became regular processional liturgy (as suggested by Radak). Nevertheless, since the construct dependent is definite, the entire construct chain must be read as definite, thus The Song of the Ascents. GKC[2] suggest this may originally have been the title of the entire collection, only subsequently added to the beginning of each psalm individually. Thus we could supply the idea of [One of] the song[s] of the Ascents, or, preferably, [Pertaining to] the Song of the Ascents.