Dottle is an an interesting word, still used in various dialects in Ireland, Scotland and England. It means a plug, a stopper. Maxwell, a Scottish agriculturalist, advised his readers back in 1743: "Have a tub, with a small hole in the bottom of it wherein put a cork or dottle in the under end." The word was common among pipe smokers in my day: it was the plug of tobacco cinder or ash remaining in the bottom of the pipe after smoking. Scotsman JM Barrie's Tommy (1896) has: "Nor did she count the treasured dottels on the mantlepiece to discover haw many pipes he had smoked." The English Dialect Dictionary reported that in Ireland dottle "is still common among labouring men."
The word could also mean any small particle or lump. The Scottish lexicographer Jamieson assures us of this; and the Ballymena Observer of 1892 tells us that “the droppings of some of the smaller domestic animals would be called a dottle.” Promptorium Parvulorum Sive Clericorum, an Anglo-Latin lexicon of c. 1440, defines Dotelle as “Stoppynge of a vessele, ducillus, dictildus.”
Dottle also meant a fool, an idiot; a dotard in Scotland and in Lincolnshire. “Johnny’s but a dottle an’ nae use ava tae any capabl wumman,” said a minor Scottish writer named Tweeddale in 1896. As an adjective the word means silly, crazy, in a state of dottage.
"Mactavish wud hae driven me dottle," wrote Ian Maclaren in Brier Bush (1895; and Latto's great Tam Bodkin (1864) has, "An'there they sat and there they drank Till baith o' them were dottle."
The verb dottle means to become crazy, stupid. Still’s Cottar’s Sunday (1845) has, “It’s gien me pain to think that Scotlan’ was dotlin.” Hence dottled, silly confused: “Jamie was rather dottled, according to his wife’s account.”
The verb also means to be foolishly fond of, to dote on. From Lincolnshire the EDD reported: “She dottles o’ the boy; she can’t abear him out o’ her sight.”
There is yet another meaning,this one from Scotland: to hobble, to walk infirmly. Hence dottle-trot, the quick, short steps of an old man, also called “the old man’s walk.” And there is dottling, hobbling, taking short, quick steps.
The word is old, from dote, from Early Middle English doten, dotien (of which no trace is known in Old English), corresponds to Middle Dutch doten to be crazy or silly, to dote. Kilian has, in same sense, doten, = dutten: cf. modern Dutch dutten to take a nap, to dote, also Middle High German totzen to take a nap, Icelandic dotta to nod from sleep.