Dire

I find trying to write my essay is a dire task.

Dire means dreadful, terrible or disastrous.

Etymology:
1560s, from L. dirus "fearful, awful, boding ill," of unknown origin; perhaps from Oscan and Umbrian and perhaps cognate with Gk. deinos, from PIE base *dwei-.

Recidivist

An habitual convict (i.e. a criminal who reoffends).
So encountered because it was used in Porridge S03E05 "A Test of Character"

Etymology
re: Latin prefix to repeat
cadere - to fall back

This then became in French recidiviste, which is where the English word came from.

Omphalos

I think it was this word in John Simpson's autobiography: "Strange Places, Questionable People". Its usual meaning is the navel - and refers to sacred conical stones at the centre of oracles. It can also be used to mean centre.