Reference: dictionaryLookup

dictionaryLookup(s) searches the currently loaded dictionary (see loadDictionary) for the entry s, a string, and returns the definition(s) of the word.

Example: dictionaryLookup("isomorphism")
           Noun: (algebra) A bijection _f_ such that both _f_ and its inverse _f_ −1 are homomorphisms, that is, structure-preserving mappings.
           Noun: (biology) the similarity in form of organisms of different ancestry
           Noun: (chemistry) the similarity in the crystal structures of similar chemical compounds
           Noun: (computer science) a one-to-one correspondence between all the elements of two sets, e.g. the instances of two classes, or the records in two datasets
           Noun: (sociology) the similarity in the structure or processes of different organizations