It seems dictionaries rarely offer definitions for adjectives that have the suffix -енький. There are a few (for instance: маленький; хорошенький), but by Googling many more show up (for instance: старенький; толстенький; весёленький). What nuance or change in meaning does -енький add to basic adjectives?
-еньк-/-оньк- is an affectionate and/or diminutive suffix, similar to English "-y/-ie": "cute / cutie, sweet / sweetie" etc.
It can be used with nouns, adjectives, adverbs and (in baby talk) even verbs: спать / спатеньки.
This suffix can sometimes change the style of even the meaning of the words it's used with: for instance, the mentioned маленький is currently the neutral word for "small, little" (малый being an archaic word, mostly used in its short predicative form мал nowadays); and хорошенький means "cute, handsome" (mere хороший does not have this meaning). That's why they are mentioned separately in the dictionary.
However, mostly the words with that suffix are just the affectionate varieties of their corresponding neutral counterparts.