A man can waste much time with an apparatus criticus and alternate readings. From Hamlet (1.1.39-43).
Peace, break thee off; look, where it comes again!
In the same figure, like the king that’s dead.
Thou art a scholar; speak to it, Horatio.
Looks it not like the king? mark it, Horatio.
Most like: it harrows me with fear and wonder.
Of the major texts, Folio has ‘harrows’, Quarto 2 ‘horrowes’, and Quarto 1 ‘horrors’. The Arden 3rd note reads:
Q2’s ‘horrowes’ is usually assumed to be an obsolete form of F’s ‘harrowes,’ a word which recurs in both texts at 1.5.16. The metaphor derives from the agricultural implement that breaks up the ground after ploughing, and OED records these as the earliest examples of the transferred use. OED also implies that there is no direct connection with ‘the harrowing of Hell’, where ‘harrow’ derives from ‘to harry’ (to raid or despoint), but, given the context of Shakespeare’s usages, there might have been a link in his mind.
The Oxord has:
harrows distresses, lacerates (OED 4). According to OED, this is the earliest use of the word in a figurative sense. Q2’s horrowes may be a varient spelling; but Q1’s horrors looks like an auditory error by the reporter.
A Synoptic Hamlet: a Critical-Synoptic Edition of the Second Quarto and First Folio Texts of Hamlet has:
horrows/ harrows Horrows: ‘horrifies’ (Andrews). Harrow: “To lacerate or wound the feelings of; to vex, pain, or distress greatly (OED 4). As Andrews suggests, in ‘horrows’ the meanings of ‘horror’ (cf. Q1’s ‘horrors’) and harrow may merge in a probable Shakesperean neologism. Cf. ‘This strikes our heart with horrowe & amazemt’ in the anonymous Jacobean play Tom a Lincoln (Proudfoot 1992: 51). In Pyle’s opinion (116), ‘horrowes’ “is simply a variant of harrows … spelling with o often occur in the 16th and 17th centuries where we should expect an a” ….. Jenkins give the examples in A Remedy of Sedition (1536), “They horrowe with spades.”
I could continue expanding references and commentary (and I wish I had the Andrews edition to add) but the short is that no one has any clear answer and everyone is willing to entertain a Shakespearean coinage – either by novel transference of meaning (using ‘harrow’ from the agricultural implement) or outright new verb formation. Accordingly, I make less an ass of myself in adding my own conjecture and connecting Q2’s ‘horrowes’ with Latin ‘horrere.’ Lewis and Short define here but I’ll cite the similar and possibly more relevant Dictionary of Medieval Latin from British Sources definition (with full usage illustrations in the link):
1 to bristle; b (fig.). c to stand up like spikes.
2 to shudder, shiver.
3 to be or become horrible, shocking, disgusting.
4 to be or become horrified.
With that in mind, advance to Hamlet’s first encounter with the Ghost (1.4.55ish):
What may this mean,
That thou, dead corse, again in complete steel
Revisit’st thus the glimpses of the moon,
Making night hideous; and we fools of nature
So horridly to shake our disposition
With thoughts beyond the reaches of our souls?
The Arden editors gloss horridly thus:
horrendously (a stronger meaning than modern ‘horrid’, possibly with a glance at the literal meaning of Latin horridus, bristing or with hair standing on end: see 1.5.19-20).
Here I would add that the DMLBS entry for horridus includes the additional sense ‘causing horror, dreadful.’ And that, bearing in mind the etymological connection with horrere and the above ‘shudder, shiver’ sense of the word, one can posit a clear play in line 55’s ‘so horridly to shake.’
Now to the second half of Hamlet’s encounter with the Ghost:
But that I am forbid
To tell the secrets of my prison-house,
I could a tale unfold whose lightest word
Would harrow up thy soul, freeze thy young blood,
Make thy two eyes, like stars, start from their spheres,
Thy knotted and combined locks to part
And each particular hair to stand on end,
Like quills upon the fretful porpentine:
Here there is no issue with the textual history – harrow is the universal reading – so I would instead draw attention to the hair imagery, which we’ve seen above is latent in the first two appearances of the ghost and directly connects to the imagery of horrere.
My vanity’s proposal is twofold. First, the less defensible element, that the harrow of 1.5 contaminated the reading of horrowes in 1.1. The only reason for preferring harrow is deference to the OED – that it feels less bold to add a new sense to an existing word than create a new one altogether. Second, that the root senses of horrere at least lurk as background associations in all three appearances of the Ghost – most expressly in the first (by my reading ‘horrowes’), more subtly in the second (submerged in ‘horridly’ but activated by ‘shake’), and as a verbal echo harrow/horrow/horrere triggered by hair-standing imagery in the third. All accomplished by a man with little Latin.
And this is why I stick to extracts. Playful and pointless argumentation takes too long.