Conjugate

The verb 'to conjugate' has more than one meaning. In its original form in Latin, it was constructed from the preposition con(-) ('together', 'with') and the verb iugare ('to yoke', 'to link').

• The basic meaning in English has always been 'to join together', most commonly in marriage or sexually. (Cells are said to 'conjugate', for example; and the word is etymologically akin to conjugal, 'to do with marriage'.)
• The commonest meaning nowadays - and not very common, at that - is to do with grammar. OED defines it as "To inflect (a verb) in its various forms of voice, mood, tense, number, and person." For more, see Declension - conjugation.