The warmest season of the year; in the northern hemisphere it extends from the summer solstice to the autumnal equinox WordNet 3.0

The warmest season of the year; in the Northern Hemisphere it extends from the summer solstice to the autumnal equinox Open English WordNet

Summer is the hottest of the four temperate seasons, occurring after spring and before autumn. Wikipedia

One of the four seasons. Wikipedia Disambiguation

One of the temperate seasons Wikipedia Disambiguation

Warmest of the four temperate seasons, beginning or centered around the summer solstice Wikidata

The time during the summer months. OmegaWiki

One of four seasons, traditionally the second, marked by the longest and typically hottest days of the year due to the inclination of the Earth and thermal lag. Typically regarded as being from June 21 to September 22 or 23 in parts of the USA, the months of June, July and August in the United Kingdom and the months of December, January and February in the Southern Hemisphere. Wiktionary

The period or season of summer. Wiktionary