The thesaurus of synonyms and related words is fully integrated into the dictionary. Click on the thesaurus category heading under the button in an entry to see the synonyms and related words for that meaning. Past participles:arisen, been, befallen... This is the British English definition of striven.
Personally, sarcasm can mean a couple of things depending on how it is dealt out. If it is sarcastic in a funny way, that person may have a sense of humor. If it is said in a mean way, than that person is probably insecure and unhappy. IMHO!
I've never really got the hang of irony. I understand sarcasm very well, but when people are saying they are being ironic, it just sounds sarcastic to me. Irony to me is when something turns out to be the complete opposite, or contradictory. I think what I'm trying to say is.. If I hear something that is contradictory..