sui generis

adjectives

constituting a class of its own; unique
"a history book sui generis"; "sui generis works like Mary Chestnut's Civil War diary"
sui generis
is similar to
existing alone or consisting of one entity or part or aspect or individual
"upon the hill stood a single tower"; "had but a single thought which was to escape"; "a single survivor"; "a single serving"; "a single lens"; "a single thickness"
single