fix

The root fix comes from Latin fīgere, meaning "to fasten, to drive in, to pierce." Picture a Roman carpenter hammering a nail to pin one board firmly to another — that single act of "nailing something so it cannot move" is the seed of the whole family. The past participle fīxus ("fastened, fixed in place") is what English actually borrowed, which is why almost every member is spelled with -fix.

From that core image, two strands grow:

The "hold in place" strand. If you nail something down, it stops moving — so fix came to mean both "fasten firmly" and, later, "make something work again" (you fix a leak by securing what was loose). fixed is simply the result: nailed down, unchanging. A fixture is a thing literally screwed into a building — a light fixture is bolted to the ceiling and stays. And fixate is the mind doing the nailing: your attention gets pinned to one thing and won't budge.

The "drive a point in" strand. Prefixes add direction to the nailing:

- ad- (to, onto) + fīgere → affix: to fasten onto something — stick a stamp on, or attach a word-part (a prefix/suffix) onto a word
- trans- (through) + fīgere → transfix: to pierce through with a spear — and figuratively, to nail someone to the spot with shock, so they stand frozen

The twist worth remembering: fīgere originally meant violent piercing (a spear driven through a body), but in modern English the gentle "fasten / repair" sense dominates. Only transfix still carries the old blade. Everywhere else, the nail just holds things steady.

One note on lookalikes: the grammar words prefix and suffix are also this root — pre-fix = fastened before, suf-fix = fastened under/after. They are siblings of affix, all built on "fasten a word-part onto a stem."