intriguing
Anecdote is an interesting or amusing story.
Atmosphere
Their is not another name for HIV that starts with an R. That said, HIV is a type of retrovirus. That is probably the word you are looking for.
Another name of a dog house is a kennel.
Rubella is another name for German measles.
S.o.s
brew
Gaucho?
Repast
Botany.
Mafia.
Noel