blister on the sole; corn
Refers to a blister or corn that forms on the bottom of the foot, often from friction or pressure.
After walking a long way in new shoes, I got a blister on the sole of my foot.
Compound of 底 (そこ, 'bottom, sole') and 豆 (まめ, 'blister'). The exact historical derivation is uncertain, but the spelling is conventionally associated with the meaning.