Afternoon is the time occurring between noon and evening. The specific range of time this encompasses varies in one direction: noon is currently defined as a constant 12:00 pm, but when afternoon ends is dependent on when evening begins, for which there is no standard definition. However, before a period of transition from the twelfth to fourteenth centuries, noon instead referred to 3 pm—possible explanations include shifting times for prayers and midday meals, along which one concept of noon was defined—and so afternoon would have referred to a narrower timeframe.
The word afternoon, which derives from after and noon, has been attested from about the year 1300; Middle English contained both afternoon and the synonym aftermete. The standard locative marking for the word was at afternoon in the fifteenth and sixteenth centuries but has shifted to in the afternoon since then. In Southern U.S. and Midland American English, the word evening is sometimes used to encompass all times between noon and night. The Irish language contains four different words to mark time intervals from late afternoon to nightfall, this period being considered mystical. Metaphorically, the word afternoon refers to a relatively late period in the expanse of time or in one's life.
The term should not be confused with "after noon" (two separate words), which is a translation of the Latin post meridiem (p.m.), meaning a time between 12:00 midday and 12:00 midnight.