The meaning of Autumn Autumn is one of the four temperate seasons. Autumn marks the transition from summer into winter usually in September (Northern Hemisphere) or March (Southern Hemisphere) when the arrival of night becomes noticeably earlier. The equinoxes might be expected to be in the middle of their respective seasons, but temperature lag (caused by the thermal latency of the ground and sea) means that seasons appear later than dates calculated from a purely astronomical perspective. The actual lag varies with region. Some cultures regard the autumnal equinox as "mid-autumn", others with a longer lag treat it as the start of autumn.[1] Meteorologists (and most of the temperate countries in the southern hemisphere)[2] use a definition based on months, with autumn being September, October and November in the northern hemisphere,[3] and March, April and May in the southern hemisphere. In North America, autumn is usually considered to start with the September equinox.[4] In traditional East Asian solar term, autumn starts on or around 8 August and ends on about 7 November. In Ireland, the autumn months according to the national meteorological service, Met Éireann, are September, October and November.[5] However, according to the Irish Calendar which is based on ancient Celtic traditions, autumn lasts throughout the months of August, September, and October, or possibly a few days later, depending on tradition. In Australia, autumn officially begins on March 1st and ends May 31st[6] According to United States unofficial tradition, autumn runs from the day after Labor Day (i.e. the Tuesday following the first Monday of September) through Thanksgiving (i.e. the fourth Thursday in November), after which the holiday season that demarcates the unofficial beginning of winter begins. Where does the word come from The word autumn comes from the Old French word autompne (automne in modern French), and was later normalised to the original Latin word autumnus.[7] There are rare examples of its use as early as the 12th century, but it became common by the 16th century. Before the 16th century, harvest was the term usually used to refer to the season, as it is common in other West Germanic languages to this day (cf. Dutch herfst and German Herbst). However, as more people gradually moved from working the land to living in towns (especially those who could read and write,the only people whose use of language we now know), the word harvest lost its reference to the time of year and came to refer only to the actual activity of reaping, and autumn, as well as fall, began to replace it as a reference to the season.[8][9] The alternative word fall for the season traces its origins to old Germanic languages. The exact derivation is unclear, the Old English fiæll or feallan and the Old Norse fall all being possible candidates. However, these words all have the meaning "to fall from a height" and are clearly derived either from a common root or from each other. The term came to denote the season in 16th century England, a contraction of Middle English expressions like "fall of the leaf" and "fall of the year".[10]