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 aforementioned маленький is, in the modern language, 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" (plain хороший doesn't have this meaning). That's why they're cited separately in the dictionary.
However, for the most part, words with that suffix are just the affectionate form of their corresponding neutral counterparts.