paklen

1. (of heat, noise, pain) hellish; infernal; unbearable
   Napolju je paklena vrućina. — It's infernally hot outside.
   U centru je bila paklena gužva. — The traffic in the centre was hellish.
2. of hell; infernal
   Grešnici se boje paklene vatre. — Sinners fear the fires of hell.
3. (of a plan, scheme) diabolical; fiendish
   Smislio je pakleni plan da ih prevari. — He came up with a diabolical plan to trick them.