abandoned
Left behind and no longer cared for or supported.
Abandoned means left behind and no longer cared for. When something is abandoned, whoever was responsible for it has given it up completely and walked away.
You might see an abandoned building in your town, with broken windows and weeds growing through cracks in the pavement. It may still have an owner on paper, but nobody is taking care of it anymore. An abandoned car sits rusting by the roadside, forgotten by its owner. Sometimes people discover abandoned pets, like a dog left outside an animal shelter, abandoned by someone who didn't want the responsibility anymore.
The word can also describe feelings. A child might feel abandoned if their friends suddenly exclude them from a game without explanation. When you feel abandoned, you feel left alone when you needed someone to stay.
You can abandon things besides physical objects: someone might abandon a plan that isn't working, or abandon hope when a situation seems impossible. In these cases, abandon means to give up on something completely rather than keep trying.
The key idea is completeness: abandoning isn't the same as temporarily leaving something behind. When you abandon something, you're walking away with no intention of coming back.