Dark or black
Nigil is a rare variant of the name Nigel, which is derived from the Latin name Nigellus. While historically associated with the Latin word for black, it was also used as a Latinized form of the Gaelic name Niall, meaning champion or cloud.
Less common today
Nigil isn't in the latest US Top 1000. It last peaked at #5,400 in 1994.
US births per 5-year period, 1990βpresent (SSA data).