Second cousin once removed

The shared ancestors are a couple who are great-grandparents to one person and great-great-grandparents to the other. The cousin degree comes from the closer person (great-grandchild level means second cousin), and the one generation of difference adds once removed.

Wiktionary records second cousin-uncle and second cousin-nephew as ways to show which way the generation gap runs. Webster's 1828 dictionary notes that cousin was also used for any more distant collateral relative, so an old record may just say cousin. Treat a label this far out as a clue to test.