How do you say neutron bomb in Latin? Scanner? Microphone? Enter the Vatican's Lexicon Recentis Latinitatis, or Dictionary of Recent Latinity. Published in two volumes (the first in 1992, the second in 1997) by Opus Fundatum Latinitas, or the Latinitas Foundation, the Lexicon covers over 15,000 words of recent vintage, from the Renaissance up to the late 20th century, and is the work of 14 experts, edited by Carolus Egger.
The original, two-volume edition is an Italian-to-Latin dictionary. There is a one-volume German-to-Latin dictionary, the Neues Latein Lexikon, as well. Apparently there is also an equivalent one-volume Italian-to-Latin edition that was published in 2003, but only in a run of 500 copies.
Some words are simply scientific, coming from Greek and Latin suffixes, prefixes, and roots. A microphone (Italian microfone) is a microphonium or a microphonum.
Similarly, a neutron bomb (Italian bomba al neutrone) is a pyrobolus neutronicus.
Some words get translated using circumlocution: a scanner (or scanner in Italian), as in a flatbed scanner, is an apparatus opticus et electronicus ad legendam imaginem: an optical and electronic device for reading images.
I have found the Lexicon indispensable for modern terms. Nevertheless, as usual, there is much argument on Vicipaedia as to the correctness of some translations. With the Internet, and especially with Google Books, it is becoming easier to research and to read original Latin texts from the Renaissance, which adds veracity to any argument.
Take, for example, the word gas, as in the third phase of matter (as opposed to gasoline). In Italian, this is gas, and the Lexicon translates this as gasium, -ii, a neuter noun of the second declension. A statement was put forward on Vicipaedia for gas, indeclinable, as the Latin term, because the located scientific usages of the term in Latin texts (from 1652, which even gives the etymology) are just that. Too, Vicipaedia has a policy, and rightly so, of not making up words, and so attested forms (preferred) or dictionary forms (if possible) must be used. If nothing is possible, then the word in the original language is used, and not Latinized.
The Latin writers, though, had no such qualms. By 1794, writers of scientific Latin, perhaps fed up with the non-Latin sound of gas as an indeclinable, had changed to gas, -is, a noun of the third declension. Then again, by 1828, into gasum, -i, a neuter noun of the second declension — a form possibly in use since 1777.
So clearly there wasn't universal agreement on the Latin for gas. Nobody ever got together at some lexicographic congress and solemnly vowed to nail down these terms. Maybe one branch went with gas, -is while another went with gasum, -i. Finding out is the type of research the Oxford English Dictionary would do.
So what does Vicipaedia do when someone wants to write about gas? The main article on gas lists all the posibilities. And, like the scientific writers of the past, different people have used different forms. Just don't get into a conversation about which term is "the right one" or "the best".