The warp is the totality of all threads (warp threads) that run in the direction of the fabric (lengthwise) during the manufacture of a fabric.
Source:
Eberle, Hannelore; Gonser, Elke; Hornberger, Marianne; et al. (2022), Fachwissen Bekleidung, 12. Auflage, Haan-Gruiten: Verlag Europa-Lehrmittel, S. 74