When looking for antonyms for the word "being concurrent," it's important to consider the various forms and interpretations of the term. In terms of time, the opposite of concurrent would be consecutive or staggered. In terms of events or circumstances, the opposite of concurrent could be divergent or disparate. Alternatively, for mathematical or technical concerns, the opposite of concurrent could be non-parallel or intersecting. Ultimately, the right antonym for "being concurrent" depends on the specific context and intended meaning. Broadly speaking, antonyms for this term are likely to involve ideas of separation, difference, or non-simultaneity.