A meadow was an area of a planetary surface covered by grass and similar plants.
In 2268, one of the irrational statements made towards the androids on Mudd by Spock was "logic is a little tweeting bird chirping in a meadow." (TOS: "I, Mudd")
The same year, upon exploring the surface of Amerind, Leonard McCoy remarked the planet was "meadows and no meteor craters", which expressed his surprise about the planet's Earth-like flora and the presence of advanced technology. (TOS: "The Paradise Syndrome")
When the Romulans brainwashed Geordi La Forge in 2367, they stimulated his brain with positive and negative images. A positive image was a spring day on Earth with a "beautiful meadow, green trees, birds, a blue sky". (TNG: "The Mind's Eye")
In 2372, Q told Kathryn Janeway that he'd bring the USS Voyager back to Earth, so she could run across a meadow with her puppies with the grass beneath her bare feet. (VOY: "Death Wish")
In 2375, the location where Benjamin Sisko planned to build a house in the Kendra Province on Bajor featured a creek running through meadows into a forest. (DS9: "Penumbra")
In the 2376 holoprogram set in 19th century Fair Haven, Mary Mulchaey fell into a well, which caused her mother to call for help. Upon return, she found Mary unharmed and in a meadow talking with Katie O'Clare, who claimed nothing had happened. (VOY: "Spirit Folk")