Incursionary refers to something related to, or involving, a sudden invasion or attack. Some synonyms for this term include: invasive, infiltrative, intrusive, penetrating, trespassing, encroaching, breaching, raiding, foraying, and entering. These words can be used to describe anything that involves an unauthorized or unexpected intrusion into a particular space or territory. For example, an invasive species that threatens to disrupt the balance of an ecosystem, or an infiltrative hacker attempting to breach a computer network. Using synonyms for incursionary can help to provide a more varied and descriptive vocabulary when discussing topics related to invasions or attacks.