1530s, from Medieval Latin connotationem (nominative connotatio), from connotat-, past participle stem of connotare "signify in addition to the main meaning," a term in logic, literally "to mark along with," from Latin com- "together" (see com-) + notare "to mark" (see note).
A word denotes its primary meaning, its barest adequate definition -- father denotes "one that has begotten." A word connotes the attributes commonly associated with it -- father connotes "male sex, prior existence, greater experience, affection, guidance."
The meaning that a word suggests or implies. A connotation includes the emotions or associations that surround a word. For example, the word modern strictly means “belonging to recent times,” but the word's connotations can include such notions as “new, up to date, experimental.”