A very common type of pseudonym, especially in the Renaissance, was a Latinisation. Examples include:
- René Descartes becomes Renatus Cartesius;
- Mikołaj Kopernik becomes Nicolaus Copernicus;
- Geert de Kremer becomes Gerardus Mercator;
- Willebrord Snel van Royen ('Snell') becomes Willebrord Snellius.
(Mathematics was not as well-established as a single profession at the time, and most of the people listed were active in many fields of science. A true Renaissance scientist is a polymath.)
Remark. For some reason, this practice seems to have been especially popular in the Low Countries. This is somewhat remarkable, given that (following Simon Stevin, another Renaissance scientist) the Dutch language dropped Latin and Greek loanwords like subtract, multiply, and even mathematics itself, in favour of the Dutch words aftrekken, vermenigvuldigen, and wiskunde. There are very few European languages that have their own word for mathematics.
Remark. One may argue that a Latinisation does not constitute a pseudonym, but if we translate pseudonym literally as false name, then any name deviating from a person's actual [legal] name can be considered a pseudonym.