sickly
1. When someone looks way too thin to be healthy 
2. Someone who is normally good looking but looks peculiarly bad either because they are ill or from lack of trying to look presentable 

1. eewww look how skinny that girl is... she looks sickly 
2. how do you feel? you're looking a little sickly today
3. you better put some makeup on or you'll look sickly