There was a post in here yesterday about a specific genus of flowers and how theyre scientifically clumps of flowers who look superficially like petals.
As long as you can defend your pick with a definition, it counts. Words have multiple definitions. Especially in different fields of knowledge. Some things may be part of a figure of speech, a saying, slang, a reference, an innuendo, etc. Or even just being non-literal. For "secret garden," if you manage to find a title (movie, drama, tv show, special) that references the movie or book "Secret Garden" it would count.
Just provide that definition/defense in the notes column of your sign up sheet. ;)