欲しし？

[緑さん]

I noticed that the IME seems to accept い-adjectives's い being replaced with し. How do i use that and to what effect does it have, or is it something archaich and no longer used?

[Toritoribe]

Right. It's from archaic grammar, like 欲す(ほっす)、欲し、欲さず、欲せども、欲さば....
It has quit different conjugations, so might cause some confusions...