The Slovak term "január" matches the English term "January"

Foreign Influences
The Slovak language shares close ties to Czech. But Czech isn’t the only language that has influenced Slovak. Polish. Hungarian, German, English, and Italian have all contributed to it too. The German word for coins, münzen, is the basis for the Slovak equivalent of mince. Thanks to English and Italian Slovak has a “vikend” or weekend and “kvalita” or “qualita” meaning quality.
The Different Dialects
Slovak has 4 different dialects; Eastern, Central, Western, and Lowland. Location has a big influence on the dialect used. In fact, Western Slovak bears the closest similarity to Czech whereas Eastern Slovak does not. But Eastern and Western Slovak do have commonalities between them.
The Impact of Dissolution
Slovak and the Czech Republic separated in 1993 and became two separate countries. Slovak became the official language of Slovak at that time as well. But up until that point, many books were still written in Czech despite the existence of a Slovak literary language.