asustar
frighten
a-
to (make)
+
scared
frightened
+
-ar
verb suffix
Asustar means to frighten and can be thought of as a-0 (to make0) + scared1 + -ar2 (verb2), literally 'to make scared'.
verb
- frightenTo frighten or scareNo quiero asustar a los niños con historias de fantasmas. // I don't want to frighten the children with ghost stories.