I've heard both used interchangeably with regards to object-[oriented/orientated] programming. What's SE's opinion on it?
I have three go-to resources for defining tech terms that I don't know: Wikipedia, Techopedia, and The Oxford English Dictionary (my public library has a subscription). All three agree that the proper phrase is "object oriented."
Wikipedia: Object-oriented programming (OOP) is a programming paradigm based on the concept of "objects", which can contain data, in the form of fields (often known as attributes or properties), and code, in the form of procedures (often known as methods).
Techopedia: Object-oriented programming (OOP) is a software programming model constructed around objects. This model compartmentalizes data into objects (data fields) and describes object contents and behavior through the declaration of classes (methods).
OED: object-oriented adj. Computing using a methodology in which a system is modelled as a set of objects (sense 7(a)) which can be controlled and manipulated in a modular manner.