Incertae Sedis

Incertae sedis (Latin for "of uncertain placement") is a term used to define a taxonomic group where its broader relationships are unknown or undefined. Uncertainty at specific taxonomic levels is attributed by incertae familiae (of uncertain family), incerti subordinis (of uncertain suborder), incerti ordinis (of uncertain order) and similar terms.

Read more about Incertae Sedis:  Examples, Lower Taxonomic Levels