Your way is a little ambiguous. Instead you should use a word that indicates a new definition. You have a couple options.
One way is to use the word significare. This is covered under II.C in Lewis and Short:
C. To mean, import, signify; of words: “carere hoc significat, egere eo, quod habere velis, etc.,” Cic. Tusc. 1, 36, 88: “multa verba aliud nunc ostendunt, aliud ante significabant, ut hostis,” Varr. L. L. 5, § 3 Müll.; “9, § 85 ib.: videtis hoc uno verbo unde significare res duas, et ex quo et a quo loco,” Cic. Caecin. 30, 88.—Of a fable: “haec significat fabula dominum videre plurimum,” Phaedr. 2, 8, 27; 4, 10, 16.
This is useful if you want to define a brand-new word or to explain the definition of a word, as in the Varro example cited above and translated below:
multa verba aliud nunc ostendunt, aliud ante significabant, ut hostis: nam tum eo verbo dicebant peregrinum qui suis legibus uteretur, nunc dicunt eum quem tum dicebant perduellem.
There are some whose origin is not from native words of our own language. Many words indicate one thing now, but formerly meant something else, as is the case with hostis ‘enemy’: for in olden times by this word they meant a foreigner from a country independent of Roman laws, but now they give the name to him whom they then called perduellis ‘enemy.’
(Trans. Roland Kent, from the Loeb)
principissa regis filia significat
princess indicates/means 'daughter of a king.'
Ostendere, declarare, and indicare are less common than significare for this purpose.
This is the way to go about it for new Latin words, but if you wanted to mark principissa as a foreign word/borrowed word, you could also use appellare. This is a frequent way for the Romans to translate individual words, as in this passage of Cicero (DND 2.53) below:
Infra hanc autem stella Mercuri est (ea Στίλβων appellatur a Graecis)
Below this is the star of Mercury (it's called Stilbon by the Greeks)
In this format, you can do something like:
filia regis principissa appellatur
the daughter of a king is called "princess"
Finally, there is no reason to put these words into the plural. Singular is just fine.