An agglutinative language in the strict definition will form words by joining together unchangable stems and affixes, where these don't fuse or change form dependent on other affixes. But "agglutinative" is also often used incorrectly as a synonym for the wider category "synthetic", which includes fusional and inflected languages (synthetic languages have a high morpheme-to-word ratio).
There some difficulties with agglutinative languages like Quechua.
- wasi — house
- wasikuna — houses
- wasita — to the house
- wasikunata — to the houses
- wasiy — my house
- wasiita — to my house
- wasiikuna — my houses
- wasiikunata — to my houses
- wasinchik — our house
- wasinchikta — to our house
- wasinchikkunata — to our houses
- etxea la casa
- etxe gorria la casa roja
- etxe gorri zaharra la casa roja y vieja
- etxe gorri zaharrarekin con la casa roja y vieja
- etxe gorri zaharrarentzat para la casa roja y vieja
This sort of complex would actually fit quite well into the current Apertium model, although each paradigm would have a great number of possible members due to the large numbers of suffixes (and this is complicated by the fact that suffix order is variable). It could also be handled by form generation, again with the drawback that many thousands of possible forms would need to be generated.
- Paradigms can refer to other paradigms, so this kind of thing should work just fine?
 Alternatives to lttoolbox
Other systems popular for agglutinative languages: