The term 'canon ending' can refer to two different crossword solutions: ize (3 letters) and ical (4 letters). The suffix '-ize' is derived from the Greek verb 'izein, ' which means 'to do or make.' It is used to form verbs from nouns, adjectives, and other verbs. For example, the verb 'REALIZE' is formed from the noun 'REAL.' The suffix '-ical' is derived from the Greek adjective 'ikos, ' which means 'pertaining to.' It is used to form adjectives from nouns, verbs, and other adjectives. For example, the adjective 'HISTORICAL' is formed from the noun 'HISTORY.'