without making a 4 letter one plural? Apsis, Annoy, Aisle, Ankle, Angle, Angel, Atoll, Annal, Agora, Anger, Angry... loads and loads of proper nouns too.
A 5 letter word that starts with an L is Lipid
butte
Aphid.
CrustCloudClingCheapClownCrownCreepCroneCease
toast
Shame
Zebra
Agree, Along
glare
potty
laugh
arena