Passive part (but with active sense) of an unused root meaning to twitter: probably the swallow -- swallow.
H5693. agur
עָגוּר noun [masculine] apparently understood by Masoretes as name of a bird; very uncertain; crane according to Saad (Isaiah), but note of crane not suitable (TristrNHB 239 f.); — וְעָגוּר וְסוּס וְתוֺר Jeremiah 8:7; עָגוּר כְּסוּס Isaiah 38:14 (but here gloss Klo Brd Di Dn CheHpt); Thes and (in Jeremiah) Hi Gf Gie strike out וְ and take ׳ע as adjective of סוס = twittering or the like; Thes assumes transpos. from גער, Ethiopic cry.
I, II, III. עַד see I. עדה. עֵד see עוד.
עֹד see עוֺד. עִדֹּא see עדד. below,
עדד (√ of following; compare Arabic count, reckon, number, period; Aramaic עִדָּנָא time).