weave, lay warp
紝 centers on the act of weaving, specifically the process of laying the warp threads on a loom. The given meanings both relate to this foundational step in textile production.
紝 combines the thread radical 糸 with the phonetic component 壬, which likely contributed the sound while 糸 indicates the meaning related to weaving or thread.
The left side is thread 糸, and the right side 壬 looks like a loom frame with a crossbar. Picture threads being stretched across the loom to lay the warp.
For ジン, imagine a weaver drinking a gin and tonic while laying the warp threads: gin -> ジン, and the threads are set straight.