Present Participle (-ens)

Present participles in Latin are formed with the suffix “-ens”. However, when these participles are put into different cases, the suffix changes to “-ent” plus an additional suffix, and it is in this form that they commonly occur in English.

Thus, from the verb “ago”, “I do”, we obtain the participle “agent”, “doing”. It was common in Latin to use free-standing adjectives as nouns, so that “agent” can also mean “one who is doing”, and this is the fundamental meaning of the word in English as well.

As an aside, the use of adjectives as nouns is not restricted to Latin—consider, for example, the title The Good, the Bad, and the Ugly. Even better, in “dinner special”, not only is “special” used as a noun, but the noun “dinner” is used as an adjective. I've been told that this reverse construction is one of the unusual features of English, and can cause much difficulty to those learning it as a second language.

Here is one more example of an English word derived from a Latin participle.

The word “president” comes from the Latin “praesideo”, meaning (unhelpfully) “I preside”. However, “praesideo” is actually a compound—it is made of the prefix “prae-” added to the verb “sedeo”, “I sit”. Thus, a president is one who sits at the front of a group or meeting.

As another aside, the word “compound” is itself a compound—it comes from the prefix “com-”, “together”, and the verb “pono”, “I place”. Then there's “prefix”, which comes from the prefix “prae-” and the verb “figo”, “I attach”. It just goes on and on, and demonstrates once again the principle that fancy words in English are often just Latin translations of the corresponding dull, ordinary words.