unsisterly

comparative more unsisterly · superlative most unsisterly

1. Not sisterly; not befitting a sister.

   Felicity tossed her golden head and shot an unsisterly glance at Dan.

   1911, Lucy Maud Montgomery, chapter 1, in The Story Girl

   2 more examples

   […] I desire I may throw myself at my father’s and mother’s feet, and hear from them what their sentence is. I shall at least avoid, by that means, the unsisterly insults I meet with from you.

   1748, [Samuel Richardson], chapter 43, in Clarissa. Or, The History of a Young Lady: […], volume I, London: […] S[amuel] Richardson; [a]nd sold by A[ndrew] Millar, […], →OCLC

   Mary was not so repulsive and unsisterly as Elizabeth, nor so inaccessible to all influence of hers […]

   1817 (date written), [Jane Austen], chapter VI, in Persuasion; published in Northanger Abbey: And Persuasion. […], volume (please specify |volume=III or IV), London: John Murray, […], 20 December 1817 (indicated as 1818), →OCLC