nosebleed
衄 centers on bleeding from the nose: a nosebleed.
衄 combines 血 (blood) with 丑, which likely contributes the sound. The character specifically denotes nosebleed.
Blood 血 flows from the nose, and the right side 丑 looks like a twisted face or a hand trying to stop the flow. Imagine a sudden nosebleed.
For ジク, picture a jigsaw puzzle piece shaped like 丑 soaked in blood 血: jigsaw -> ジク, and the blood drips from your nose.
defeat; loss