Etymology From Middle English thakken (“to stroke”), from Old English þaccian (“to touch gently, stroke, tap”), from Proto-West Germanic *þakwōn, from Proto-Germanic *þakwōną (“to touch lightly”), from Proto-Indo-European *teh₂g- (“to touch”). Cognate with Old Dutch þakolōn (“to stroke”), Old Norse þykkr (“a thwack, thump, blow”), Icelandic þjökka, þjaka (“to thwack, thump, beat”), Norwegian tjåka (“to strike, beat”), Latin tangō (“touch”). More at thwack, tangent.
1
Dialectal To strike or thump (someone or something); to thwack.
Obsolete except UK
thack
noun
Etymology From Middle English thacce, from thakken (“to stroke”): see etymology 1.
1
A stroke; a thwack.
thack
intj
Etymology From Middle English thacce, from thakken (“to stroke”): see etymology 1.
1
The sound of a thack.
1860, Albany Fonblanque, Jun., Hector Mainwaring; or, A lease for lives, Ward and Lock, page 205, Thack ! thack ! thack ! the heavy hunting whip came down upon the head and shoulders of Charles Dudley.
Whishhh—THACK! The strap is a blur as it comes to meet my outstretched hand.2012, Campbell Bolwell, From the Mountaintop, Xlibris, page 33:
thack
noun
Etymology From Middle English thak, thakk, thakke, from Old English þæc, from Proto-West Germanic *þak, from Proto-Germanic *þaką, from Proto-Indo-European *teg-. Cognate with Dutch dak, Low German Dack, Danish tag (“roof”), German Dach (“roof”), Old Norse þak (“thatch, roof”). Akin to Latin toga (“garment”) and Ancient Greek στέγος (stégos, “roof”). See also thatch and deck.
1
The weatherproof outer layer of a roof, often specifically thatch.
This outer layer was generically known as 'thack', but, owing to the fact that the vast majority of buildings in early times were covered with a thacking of straw or some similar material, 'thatch' gradually acquired its modern restricted significance of straw, or reed, heling.1952, L.F. Salzman, Building in England, page 223:
Etymology From Middle English thak, thakk, thakke, from Old English þæc, from Proto-West Germanic *þak, from Proto-Germanic *þaką, from Proto-Indo-European *teg-. Cognate with Dutch dak, Low German Dack, Danish tag (“roof”), German Dach (“roof”), Old Norse þak (“thatch, roof”). Akin to Latin toga (“garment”) and Ancient Greek στέγος (stégos, “roof”). See also thatch and deck.
1
To cover a roof with thack.
The said day, it was represented that the thacking and covering of Houses houses in the towne with straw and hedder wes very dangerous, and rendered them obnoxious to fyre, and to the endangering of the saids houses and the neighbouring adjacent houses, and that a fatall evidence thereof, by haveing some houses thacked and covered as said is, had falne out in the Gallowgate lately; […] .2023 [1871], John Stuart, Extracts from the Council Register of the Burgh of Aberdeen, Outlook Verlagsgesellschaft (Anatiposi Verlag), Books on Demand, page 365, 28 June 1716