algo-

Pain.

Greek algos, pain.

Algology is the branch of medicine concerned with the study of pain (a word of the same spelling, but from Latin alga seaweed, refers to the study of algae); a person who studies this specialism is an algologist; algophobia is an abnormal fear of pain; and algolagnia (Greek lagneia, lust) is a desire for sexual gratification through inflicting pain on oneself or others, sadomasochism.