In its contextual menu LO-Writer already offers Synonyms and Thesaurus features.
It would be ideal to also include “Search in Wikipedia”, “Search in the Web”, and “Look Up in Dictionary” options.
Thank you very much for your wonderful work
@EnekoGotzon – Still interested in an Answer to your question?
@manj_k – could you turn your comment into an Answer so we can try to resolve this question if we don’t hear back from OP?
(Modified my comment to an answer)