There are many Latin adjectives in current use. An understanding of adjectives and romance languages can help you to understand what Latin words can still be used as adjectives today.

An adjective describes a noun or a pronoun; it gives the reader or listener more information. The words “a,” “an,” and “the” are adjectives. The following are some examples and explanations of different kinds of adjectives.
Some adjectives express degrees of modification, like “rich, richer, and richest,” or “pretty, prettier, or prettiest.” Another example is good, better, best. These three levels of comparison are called “positive,”” comparative,” and “superlative.” However, some adjectives can not have three levels or even two levels of comparison. Examples of these are: impossible, complete, final, perpetual, universal, whole, devoid, ideal, and minor.
More than half of the words in the English language are nouns. Adjectives make up about one quarter of the words, and verbs make up around one seventh. The rest of the words is everything else: conjunctions, prepositions, exclamations, etc.
Some Latin adjectives in current use are used often enough so that they are familiar to many people. One of them is the word “emeritus” which refers to a person who has retired or been discharged from a position but retains the title of that position. In Latin, the word means “having fully earned” so it is used to honor the person.
Another example is the word “fidelis.” It means “faithful” or “trustworthy” and is well known for its use in the phrase “Semper Fidelis” which is the motto of the US Marine Corps and is sometimes shortened to “Semper Fi.”
“Gratis” means you are getting something free. “Gratis” is the plural of the word “gratia” which in Latin means “favor” or “kindness.” The word “simplex” means “simple, pure, or single.”
Following are a few examples of the most common Latin adjectives in current use today:
Latin was spoken in Ancient Rome and is not spoken today. It is one of the languages in the Indo-European language family. Latin is also a member of the Italic subfamily which includes the Romance languages.
The Romance languages have all been derived from Latin. There are about 25 of them spoken in the world today. The Romance languages include: Italian, French, Portuguese, Spanish, Catalan, Romanian, Sicilian, Neapolitan, Corsican, and Venetian.