Crackpot
What's the meaning of the word 'Crackpot'?
A crazy person; a crank.
What's the origin of the word 'Crackpot'?
There are countless words in the language that began as two-word terms, later to become hyphenated and later still to merge into a single word, for example, 'zigzag', 'forewarned', 'ninepence' etc. Crackpot is on that list.

To discover its origins, we need to ignore the Vikings and realise that 'crackpot' is a shortened form of 'cracked-pot', which splits into its constituent parts, cracked and pot.
Cracked:
Cracked is itself a shortening of 'brain-cracked' (or cracked-brained'). 'Cracked' simply meant 'impaired'; 'faulty'. Both of these terms were current in the 17th century. For instance, in Randle Cotgrave's, A dictionarie of the French and English tongues, 1611, we find:
Estropié de caboche, ou de ceruelle, frantick, witlesse, braine-sicke, brain-crackt.
And in John Canne's A Necessity of Separation from the Church of England, 1634, we find:
If Mr. Bradshaw had found such a reason in Mr, Johnson's writing, he would surely have called idle head, cracked-brained, fool etc.
Pot:
In the Middle Ages, 'pot' was used to mean 'skull' or 'head'; for example, this piece from Guy de Chauliac's translation of Grande Chirurgie, circa 1425:
Ye pot of ye heued
So, a 'cracked pot' was a 'faulty head' and crackpot is synonymous with our more recent terms 'numbskull', 'blockhead', 'brain-dead' etc.
The first record that I can find of the term 'crack-pot' (with a hyphen at that stage) is in a Broadside Ballad, recorded by John S Farmer in 1883:
My aunty knew lots,
and called them crack-pots.
