Pain, usually in a specified part of the body.
Greek algos, pain.
Most words ending in ‑algia are specialist medical terms, but a few are more generally known, such as neuralgia, intense intermittent pain along the course of a nerve.
One that seems not to fit here is nostalgia, a sentimental longing or wistful affection for the past; this first entered the language meaning homesickness (Greek nostos, return home), hence having a sense close to ‘pain of separation’.
A few terms have linked adjectives in ‑algic, for example arthralgic, myalgic, neuralgic, and nostalgic.
Examples of words in -algia
Word origins are from Greek.
pain in a joint
arthron, a joint
severe burning pain in a limb caused by injury to a peripheral nerve
kausos, heat or fever
a disease caused by dilation of the peripheral blood vessels, associated with burning, redness of the skin, and pain
eruthros, red, plus melos, limb
pain in the stomach
gastēr or gastr‑, stomach
pain in the breast caused by congestion during lactation, or other causes
pain in a muscle or group of muscles
intense, typically intermittent pain along the course of a nerve, especially in the head or face
neuron, a nerve
a pain associated with some abnormal condition in a bone
ōtalgia, from ous or ōt‑, ear
stabbing pain in the face, also called trigeminal neuralgia
pain in or due to the spine