Perhaps from badad (in the sense of divided fibres); flaxen thread or yarn; hence, a linen garment -- linen.
see HEBREW badad
H906. bad
I. בָּ֑ד בַּד, noun [masculine] white linen (derivation unknown) plural בָּ֑דבַּ֯דִּים אֵפוֺד 1 Samuel 2:18 (Samuel), 22:18 (priests of Nob), 2 Samuel 6:14 = 1 Chronicles 15:27 (David): in P as material of different priestly vestments Exodus 28:42; 39:28; Leviticus 6:3 (twice in verse); 16:4 (4 t. in verse); 16:23, 32. Plural (הַ)בַּדִּים (ה)לבושׁ clad in (the) linen garments, of angel Ezekiel 9:2-3, 11; 10:2, 6, 7; Daniel 10:5; 12:6-7,.