systeemien
Systeemien is not a recognized Dutch word. In standard Dutch, the plural of systeem is systemen. The form systeemien is not listed in major dictionaries and is rarely used, typically appearing only as a misspelling, a neologism in speculative writing, or within a specific author’s invented vocabulary. As such, there is no widely accepted definition or usage in mainstream linguistics or scholarship.
When encountered, its meaning is usually inferred from context. It may be a typographical error for systemen,
Usage guidance: In formal writing, prefer systemen and provide a clear definition if you choose to use