Each of the dictionary's headwords is defined in Esperanto, along with additional information, such as example sentences, to help distinguish the subtle shades of meaning that each particular word form may have.

Italian, Bulgarian, Romanian, Persian, Indonesian, Swedish, Breton and several other languages are also represented, though with smaller numbers of Esperanto headwords.

[2] In addition to indices of headwords linking to the various national languages represented, Reta Vortaro also has multiple thematic indexes, a thesaurus and a bibliography of sources consulted.

The original purpose had been to create an electronic version of the massive dictionary known as Plena Ilustrita Vortaro de Esperanto (1970 and 2002 editions), but due to a lack of interest on the part of the PIV editors, at least partly due to concerns at the time over harming sales of the printed volume — since alleviated, as PIV now has both a reprinted paper edition and a free online version — the Reta Vortaro project changed its focus to creating a separate Internet-use dictionary.

In addition, the dictionary had large thematic vocabulary subsets, with geography at 1298 words; mathematics at 1,290; zoology at 1,108; politics, sociology and administration at 1,069; botany at 1018; medicine and pharmacy at 809; economics, finance and commerce at 762; technology at 620; cooking at 564; chemistry and biochemistry at 510; computer science at 497; music at 491; history at 446; etc.