The phrase "stochastic nature" refers to something that is unpredictable or random. It means that it's affected by chance and can't be easily determined or controlled. Full definition
Researchers used this net of energy relationships to account for the stochastic nature of the Langevin model and represent some key fluctuation - dissipation dynamics associated with Uranium scission points. (sciencedaily.com)
Given the stochastic nature of planetary accretion, each realization of a protoplanetary disk will be modeled ~ tens of times in order to provide statistically significant outcomes that will allow us to quantify the confidence of results. (eos-nexus.org)
This is caused by the stochastic nature of plasmid uptake by cells. (blog.addgene.org)