Jackal, jaguar, jellyfish and jungles are scary. They begin with the letter J.
JAWS
gas
egis
uvea
east
hums
Aper
Some four letter words beginning with Y are:yardyarnyawnyearyellyelpyokeyolkyouryurt
span
ibex idea idol into item
yarn, year, your, yaks
x-ray
Abet