"theory or practice of cladistic taxonomy," 1966, from clade + -ism. Related: Cladist.

"faith and practice of the Catholic church," 1610s, from Catholic + -ism.

"one versed in the theory and practice of education," 1815; see education + -ist.

"the practice of systematic or persistent obstruction," especially in a legislative body, 1868, from obstruction + -ism.

"practice of conveying instruction; tendency to be didactic in style," 1841; see didactic + -ism.

1560s, "practice of using thieves' cant," verbal noun from cant (v.1).

late 15c., "quality of being foolish," from foolish + -ness. From 1530s as "a foolish practice."

"having experience, taught by practice, skillful through doing," 1570s, past-participle adjective from experience (v.).

"of or characteristic of a declamation," 1580s, from Latin declamatorius "pertaining to the practice of speaking," from declamatus, past participle of declamare "to practice public speaking, to bluster," from de-, here perhaps an intensive prefix (see de-) + clamare "to cry, shout" (from PIE root *kele- (2) "to shout").

c. 1200, "act of employing," from Anglo-French and Old French us "custom, practice, usage," from Latin usus "use, custom, practice, employment, skill, habit," from past participle stem of uti "make use of, profit by, take advantage of" (see use (v.)).