1) A regional word for brushwood, used as a fencing material.
Wright found it in parts of north Wales and the midland counties, and the OED has an example in Nottinghamshire in 1486. In 1436 Wakefield tenants were charged with felling and carrying away ‘green wood called Tynsill in the Out-wood’ and a Bradfield court roll for 1440 has the latinised form tynsellum, which the editor translated as ‘rails’. The word was in regular employment in Yorkshire, and Jackson quotes a document dated 1473-4 in which tynsell was to be used for making and repairing a weir and mill dam. Occasionally it occurred as a verb: 1518-9 to tynsell, to hegge Aboute the same mese, Tong. In a later lease it was linked with ‘trouse’: 1593 liberty to cut down and carry away [certain wood] leaving … sufficient crops, lops, bushes, trowse and tynsell for the mowndinge, fencing and hedging of the demised premises, Bingley. It can be compared with ‘tinnet’ found in other English regions, and with ‘garsil’, another Yorkshire word for brushwood which has a similar suffix. It may be the origin of place-names such as Tinsel in Midgley and even Tinshill in Adel.
2) Used of satin or other fabrics which were made to sparkle by the interweaving of gold or silver thread.
1558 one sute of rede silk tynselde with borders of Images of soundry saynts, Middleton in Teesdale
1568 A tester of Russet velvet tinsell fringed with Russet Silke and golde, Healaugh Park.