reciprocant
/rɪˈsɪprək(ə)nt/Mathematics
noun
An expression involving derivatives of a function y with respect to a variable x which has the same form (up to multiplication by a factor) when expressed with derivatives of x considered as a function of y. Now historical.
Origin
Mid 19th century (in an earlier sense). From classical Latin reciprocant-, reciprocāns, present participle of reciprocāre.