a commercial roadside inn: a paid public lodging where any traveler could stop for the night
This word names a wayside inn, the kind of paid public lodging a traveler in the ancient world would pay to sleep in on a long road. Its parts literally mean "a place that receives everyone," and that is exactly what it was: a roadhouse open to all comers, run by a proprietor for money, quite unlike staying as a guest in a private home.
Luke uses this precise word only once, in the parable of the Good Samaritan (Luke 10:34), where the Samaritan carries the beaten man to an inn and pays the keeper to care for him. Luke is careful with his words for lodging. Elsewhere he uses a more general term (kataluma) for a private guest room, such as the room where there was no space for Mary and Joseph and the upper room of the Last Supper. Here he reaches for the specific commercial word instead, marking this as a paid public inn with a hired keeper, not someone's spare room.
In the wider Greek and Jewish world of the time, inns like this had a rough and often shady reputation. Ancient writers and later rabbis pictured them as dirty, unsafe places tied up with cheating, prostitution, and worse, and innkeepers were a stock figure for dishonesty. That background gives the Samaritan's action extra force: he brings a vulnerable stranger to just the sort of place respectable people were taught to avoid, pays in advance, and promises to cover whatever more it costs, trusting the keeper to do right by the wounded man.
Early Christian writers loved that the word means "the place that receives all" and read the inn as a picture of the church, which takes in everyone. That is a later devotional reading rather than what the word itself means, but it caught something true about the story.