jizzn.

1922 T. A. Coward Bird Haunts & Nature Memories 141 A West Coast Irishman was familiar with the wild creatures which dwelt on or visited his rocks and shores; at a glance he could name them, usually correctly, but if asked how he knew them would reply ‘By their “jizz”.’ What is jizz?..We have not coined it, but how wide its use in Ireland is we cannot say... Jizz may be applied to or possessed by any animate and some inanimate objects, yet we cannot clearly define it. A single character may supply it, or it may be the combination of many.

1922 T. A. Coward Bird Haunts & Nature Memories 143 Jizz, of course, is not confined to birds. The small mammal and the plant alike have jizz.

1950 Brit. Birds 43 29 Miss Quick obviously looks at her birds more than once and does so with an artist's eye for those peculiarities of shape, outline and stance which give a species its ‘jizz’.

1960 Times 14 June 14/7 The boy could name any bat at a glance..(an indefinable accomplishment which the late T. A. Coward..once described as ‘jizz’ when speaking of bird identification).

1966 D. McClintock Compan. Flowers ix. 117 I know only too well the problem of trying to express what there is in a plant that enables me, or you, to tell it from another at sight. The word I use for these intangible characteristics, that defy being put into words, is jizz.