Niilo is of Finnish origin, derived from the word 'niil' which means 'cold'. It is a unisex name, traditionally given more often to boys than girls. The name gained popularity in Finland during the mid-20th century and has since become quite common. Niilo was the 17th most popular boy's name in Finland in 2019. There are no significant variations of Niilo in other languages or cultures, maintaining its Finnish identity.
The name Niilo experienced periods of popularity and decline over the past century, with a notable increase in recent years.