From an unused root (meaning to liquify); asphalt (from its tendency to soften in the sun) -- pitch.
Englishman's Concordance
1) pitch, tar, asphalt Part of Speech: noun feminine A Related Word by BDB/Strong’s Number: from an unused root (meaning to liquify) Same Word by TWOT Number: 572
Brown-Driver-Briggs
זֶ֫פֶתnoun feminineIsaiah 34:9pitch (compare on formative Ol§ 164 c) Sta§ 187 a. Word is Armenian according to LagArm. Stud. 1351, BN 219; on Egyptian derivatives compare CookSpeaker's Comm. i. 484; Arabic according to Frä151, if Shemitic, is Aramaic loan-word; see also Ethiopic Di1068) — pitch: — וַתַּחְמְרָה בַחֵמָר וּבַזָּ֑פֶתExodus 2:3 of ark of bulrushes; Isaiah 34:9 a וְנֶחֶפְכוּ נְחָלֶיהָ לְזֶפֶת וַעֲפָרָהּ לְגָפְרִ֑ית, Isaiah 34:9 b והיתה אַרְצָהּ לְזֶפֶת בֹּעֵרָֽה׃.
Exodus 2:3 HEB:וַתַּחְמְרָ֥ה בַחֵמָ֖ר וּבַזָּ֑פֶת וַתָּ֤שֶׂם בָּהּ֙ NAS: it over with tar and pitch. Then she put KJV: it with slime and with pitch, and put INT: and covered tar and pitch put the child
Isaiah 34:9 HEB:וְנֶהֶפְכ֤וּ נְחָלֶ֙יהָ֙ לְזֶ֔פֶת וַעֲפָרָ֖הּ לְגָפְרִ֑ית NAS: will be turned into pitch, And its loose earth KJV: thereof shall be turned into pitch, and the dust INT: will be turned streams pitch loose brimstone
Isaiah 34:9 HEB:וְהָיְתָ֣ה אַרְצָ֔הּ לְזֶ֖פֶת בֹּעֵרָֽה׃ NAS: will become burning pitch. KJV: thereof shall become burning pitch. INT: will become land pitch burning