From the same as pash as in the sense of comminuting; linen (i.e. The thread, as carded) -- flax, linen.
see HEBREW pash
H6593. pesheth
[מֵּ֫שֶׁת] noun [masculine] flax, linen (√ dubious; Late Hebrew מִּשְׁתָּן, Punic φοιστ; Löwp. 233); — suffixמִּשְׁתִּי Hosea 2:7; 2:11; elsewhere plural מִּעשׁתִּים Judges 15:14 +, construct מִּשְׁתֵּי Joshua 2:6; —
1 flax, after gathering, הָעֵץ מִּשְׁתֵּי Joshua 2:6 (J E, see עֵץ
2f); inflammable Judges 15:14 (simile); as natural product (+ עֶמֶר) Hosea 2:7; 2:11; as material, פ ׳מְּתִיל Ezekiel 40:3; of various garments Jeremiah 13:1; Ezekiel 44:17-18, (twice in verse), + צֶמֶר Deuteronomy 22:11; Leviticus 13:47-48, 52, 59 (P), compare Proverbs 31:13; פ ׳עֹבְדֵי שְׂרִיקוֺת Isaiah 19:9 (see [ שָׂרִיק]).