There are literary hundreds of Latin words in all European languages and we can easily trace their origins back to the times when Roman legions were making way for the civilization as we know it. But do not worry, this list will not contain this kind of words. We will focus only on the really ancient ones.
NOTE: This is by no means a definitive list, just a quick scan of the BASIC Latin dictionary. I avoided the words that are not obvious cognates but could possibly be related. Slavic words are based on the Serbian language, but most of the words are common for all Slavs.
A few basic terms
MARE – MORE (SEA) IGNEUS – OGANJ (FIRE) ULIGO – VLAGA (HUMIDITY) NEBULA-NEBO (CLOUD-SKY)
MUS – MISH (MOUSE) AGNIS – JAGNJE (LAMB), OVIS – OVCA (SHEEP) CABALLUS – KOBILA (HORSE)
OCULUS – OKO (EYE), POLLEX – PALAC (THUMB) CRUOR – KRV (BLOOD) OS – USTA (MOUTH)
MOLO – MLETI (MILL, TO GRIND) STO – STOJATI (TO STAND), SEDEO – SEDETI (TO SIT), VIDEO – VIDETI (TO SEE), ITIO – ICHI (TO GO) SECCARE – SECHI (TO CUT), PROSECO – PRESECHI (TO CUT OFF)
LAEVUS – LEVI (LEFT) DOMUS – DOM (HOME) TU – TI (YOU), TIBI – TEBI (TO YOU) OLEUM – ULJE (OIL) PRAE – PRE (BEFORE), PROD – PRED (IN FRONT), PROVIDUS – PROVIDJENJE (PROVIDENCE) CASTUS – CHIST (PURE), CASTITAS – CHESTITOST (MORAL PURITY) VOLUNTAS – VOLJA (WILL)
POLIS (CITY) – POLJE (FIELD) GRANUM (GRAIN) – ZRNO
This is where it gets really interesting. In Latin “Polis” means “city”, but in Slavic “polje” means “field”. Constantinople, for example, is “Konstantinopolj” in Slavic and these words are obvious cognates. However, the Roman goddess of pastures is “Pales“, which does not make any sense, unless related to the Slavic meaning of “field”.
SUUS, (but in gen, dat, voc and nom SVAE) – SVOJ (of oneself, belonging to oneself, his own, her own, his, her, its, their)
SUM – SAM (I AM), EST – JESTE (IT IS)
In both of these words, we see that Slavic form is more complex, as “sam” is just a short form of “jesam” (I am). It is therefore impossible that Slavs took this word from Latin.
VIVIR / VITA (TO LIVE / LIFE) – ZHIV / ZHIT
The sound “ZH” is typical for Slavic languages, although it survived in French and Portuguese as well. Latin did not have it, so it became “V”. It is possible that “ZH” becomes “V” but not vice-versa, meaning that the Slavic pronunciation is older.
LUX – LUCH (LIGHT), NOX – NOCH (NIGHT)
Now, we know that the letter “X” came to Latin via Greek “Chi“, where it was (apparently) pronounced as “Kh”. This means that if we read Latin with the original Greek pronunciation we get very close to Slavic words. (!) In Balkans, unlike in Russia and Ukraine, it is actually two sounds of different softness (Ч + Ћ). Also, it seems that this was not only a pre-Roman sound. It can still exist today in Italian and Spanish (ie. Buena noches in Spanish)
And while the etymology of the word “lux” in Latin is unknown, the Slavic one is related to the wood of the pine tree that is drenched in resin. When the wood is cut it excretes resin in order to heal itself. This type of wood is perfect for starting the fire, as it is easy to light and it burns for a very long time. The word for the resine is “luch”, and comes from “luchiti” which in Slavic means “to drench, secrete”. Obviously, this is the reason that the light is called “luch” in Slavic. Here is the Wikipedia article about luch (only in Serbian unfortunately).
Note that this type of parallel does not exist in Latin. The word resin has the same root as English – resina. But there is another Latin word – lac. The official etymology is on an image below.
Caminus – Kamen
The Latin word Caminus, comes from the ancient Greek “kámīnos“. According to Wiktionary, the suffix “-ῑνος” is pre-Greek and the etymology is unknown. The only suggested connection is with Slavic kamen – stone, as the ancient hearths were made of stone.
Procus / Proci – Prosac / Prosci
The Latin word Procus (genitive Proci), meaning “wooer, suitor” actually comes from ancient Greek, and it is at least as old as the Odyssey. Namely, this was the term used for the suitors of Penelope in 750 BC.
The Indo-European root of this word, reconstructed as “Prek” is fairly common in many languages, from Sanskrit and Tocharian, to Indo-Aryan, Balto-Slavic and Celtic.
However, most of the modern derivates have undergone certain changes. In Slavic languages, however, the word is virtually unchanged – “prositi” means both “to ask” and “to propose”. At the same time, the term for suitors would be “prosci”, strikingly similar to the “proci” of the Odyssey.