开放 ("to open up") +
性 ("-ness"). Wide range:
开放性问题 (open-ended question, in education),
开放性骨折 (open fracture, in medicine),
经济开放性 (economic openness),
开放性结局 (open-ended ending, in film criticism). The
性 suffix turns adjectives/verbs into abstract nouns, like English "-ness" or "-ity."