"Rōvra issi?"

Translation: Are they big?

[NLiddy10]

How would you ask "Is it big?"

[BrunoSenra]

"Rōvor issa?" would be singular, but I'm confused about the use of adjectives without any nouns. Why would we assume "they" to be aquatic? Would this only happen in a specific context when it's implicit? Hmmm

[FelipeKail.an]

Rōvra issa?

[ojygya]

Wouldn't make grammatical sense as 'rōvra' is plural and 'issa' is singular.

[Etromin1]

Does HV always put an undefined referent in the aquatic?