Like other Dravidian languages, Tamil is an agglutinative language which means that suffixes are added to stems for derivation and for expressing various grammatical relationships. There is no absolute limit on the length and extent of agglutination in Tamil. This can result in very long words. Take for instance, which means "for the sake of those who cannot go" (Wikipedia). As you can imagine, such long agglutinated words can be a translator's nightmare.