Science words in Esperanto: Rule 15 and kemio

Scientific words come into Esperanto whole and then take Esperanto endings: kemio gives kemia and kemiisto. The -ik- and -ologi- inside them are mostly not suffixes you may reuse. And the history is short: Esperanto never became the language of science, but it produced the man who organised science's vocabularies.

Rule 15: import whole, then derive

Rule 15 of the Fundamento, in its own English column:

The so-called "foreign" words, i. e. words which the greater number of languages have derived from the same source, undergo no change in the international language, beyond conforming to its system of orthography. Such is the rule with regard to primary words, derivatives are better formed (from the primary word) according to the rules of the international grammar, e. g. teatr'o, "theatre", but teatr'a, "theatrical", (not teatrical'a), etc.

Two steps. Import the base word whole, in Esperanto spelling:

Then derive with Esperanto, never with the source language:

• La kemia laboratorio estas granda. - The chemistry laboratory is big.
• Ŝi estas sciencisto. - She is a scientist.
• Tio estas biologia demando. - That is a biological question.

If you have read science in a European language, you already know hundreds of these roots.

Looks like a suffix, is not one

Learners who know -ejo and -ilo see biologio and expect an -ologio suffix. Mostly there is none: the words came in whole, as affixes as words explains.

-ik- is the trap. Fiziko names a field, but trafiko is traffic and maniko is a sleeve. Reading -ik- as a suffix would make dozens of words seem to mean something else, so PMEG's advice is oni lasu ĉi tiajn internaciajn vortojn en paco: leave these international words in peace.

-olog- works only narrowly. PMEG says it is used almost only where a matching international word exists: kancerologo for an oncologist. Do not invent an -ologio for cookery.

-it- is for medicine. Orelito is an ear inflammation. In everyday language PMEG prefers the plain word: orela inflamo.

-eno: dodging -in-

-In- makes a female, so an imported word ending in -ino can look like a female form. For some words, Esperanto chose -eno instead:

Platinum is both plateno and platino, and PMEG calls both perfectly good words. Not every -ino changed: in urino, urine, and medicino, medicine, the -in- is only a look-alike inside a single root.