Seamus Heaney, in the first poem in his new collection, Electric Light, calls the fish, perch, grunts. It is a northern word, mentioned in W.H. Patterson's glossary from Down and Antrim, sent to the editor of the embryonic English Dialect Dictionary in 1880; nobody seems to know what its origin is. The word is not in any of the Scots or English dialect dictionaries, as far as I know, but another poet knew it. Elizabeth Barrett Browning, in her 1851 Casa Guidi Windows has: "The pool in front Where in the hillstream trout are cast to wait The beatific vision, and the grunt Used at refectory, keeps its weedy state". As it did in Heaney's perch, swimming "Near the clay bank in alderdapple and waver".
Waver sent me searching. I found a few glosses from Ted Hughes's country which might interest his friend: (a) young tree left standing when the surrounding wood is felled; (b) a twig shooting from a fallen tree; (c) a small waving twig. Is the latter one Heaney's meaning? The first two meanings are from Middle English weyven, from Anglo-French weyve-r, from Old French gaiver. Hence the law term waiver; hence waif. The third is from Old English waifian, to move to and fro, corresponding to Old Norse vafa, to swing, vibrate.
Glar is here in adjectival form, glarry. Glar is Ulster mud. The Donegal Irish is glar, but that's a borrowing. But from where? From Scots, certainly, but further back? We can only guess. Oxford tentatively suggests a glossary Promptorium Parvulorum Sive Clericorum: "gloryyn or wythe onclene thynge defoylen, maculo, deturpo". Another guess: the Old Norse leir, mud.
Whatever it's origin, glar, a verb as well as a noun, has had many an outing in Scots and Northern English literature, as glaur very often. "No son of mine shall be speldering in the glour", wrote Stevenson in The Weir of Hermiston, in 1896. "How ye've whammeled 'mang the glar" is a line from a poem in Borderland Muse, a little book written in Northumberland in 1896, that I bought at a Kilcoole Horse Show stall 25 years ago, for a shilling. And what about this from that robust Scot, Henryson, written about 1450: ". . . That suld presume with thy foull lipyis vyle, To glar my drink, and this fair watter fyle".
And that, Seamus, is my poor ha'p'orth of thanks for a treasured poem. Fan og!