tum

The whole tum- family grows from one vivid image: Latin tumēre, 'to swell, to bulge, to be puffed up.' Picture a balloon filling with air, or a bruise rising on the skin. Everything in this family is some version of that swelling — sometimes a real lump of flesh, sometimes a swelling of noise, sometimes a swelling of the ego.

Start with the literal body. A tumour (American tumor) is, at root, simply 'a swelling' — Latin tumor meant any abnormal lump, long before modern medicine narrowed it to a mass of cells. The adjective tumid describes anything swollen: tumid flesh, a tumid river after rain. The abstract noun intumescence names the process or state of swelling up — literally 'a swelling within' (in- + tumēre).

Now watch the metaphor stretch. When a crowd 'swells up' with noise and movement, you get tumult — from Latin tumultus, the swelling of a mob into uproar and confusion. The image is a sea of people heaving like a rising tide. From there came tumultuous, the adjective for anything stormy, chaotic, or wildly agitated.

The most interesting branch swells in a different direction: the ego. When the prefix con- (an intensifier here, 'thoroughly') joins tumēre, you get the idea of someone puffed up with self-importance — too inflated to obey anyone. Contumacy is exactly that: stubborn, swollen-headed defiance of authority, especially refusal to obey a court. Its cousin contumely is the insolent, sneering treatment that a puffed-up person hands out to others — haughty contempt, scornful abuse.

So the logic chain is: swell → a lump (tumour, tumid, intumescence) → a swelling of noise (tumult) → a swelling of pride (contumacy → contumely). Two more modern relatives keep the bodily sense alive: tumescent ('becoming swollen') and its opposite detumescence ('the subsiding of a swelling'). Once you see tum- as 'bulge,' every member of the family snaps into focus.