A trade route, or commmercial lane, was a network of locations which was regularly used in the commercial transport of cargo.
In the mid-22nd century two Osaarian merchant ships entered the Delphic Expanse to search for new trade routes. (ENT: "Anomaly (ENT)")
When Enterprise discovered a mysterious vessel in 2152, it was more than thirty light years from the nearest trade route. (ENT: "Future Tense")
Alixus chose Orellius as the site of her colony in 2360 since it was far from any trade route and "completely isolated". (DS9: "Paradise")
By 2366, the raids of the Gatherers had disrupted Federation trade routes in the vicinity of Acamar III. (TNG: "The Vengeance Factor")
Galorndon Core was along the Barolian trade route with the Romulan Star Empire in 2368. (TNG: "Unification II")
In 2370, Galador freighters operated on a trade route between Galador II and Farius Prime. (DS9: "The Maquis, Part I")
By 2372, Bopak III was well off established Gamma Quadrant trade routes. (DS9: "Hippocratic Oath")
According to Adin in 2373, a trade route close to Ilari was often plagued by mercenaries and thieves. (VOY: "Warlord")
In 2376, Gedrin initially claimed the Vaadwaur had used the underspace as trade routes, though they had in fact used it to attack and conquer other planets. (VOY: "Dragon's Teeth")