The -ios/-i̯os nouns/adjectives usually meant the origin or belonging of the thing, for instance, nea̯ui̯os "of a ship", smğelbhi̯os "of the same womb, uterine", su̯oini̯os "wife's sister's husband" (from su̯oinia̯ "wife's sister"), su̯esri̯os "sister's son". This possibly developed from Locative case whose ending was -i. Thus, su̯esri would mean "at the sister", nea̯ui would mean "on a/the ship". Also used as comparative as in seni̯os "older".
The -ter nouns meant agents. Those whose job, work, or design was to do some function. Thus, censter meant "speaker", doma̯ter meant "tamer", peq̆ter meant "cook". This suffix also was used for the terms for relatives.
The -tor suffix also created the agent noun but it meant somebody who did the action irrespective of whether it was his usual occupation. Thus, if peq̆ter meant "cook", peq̆tor would mean the one who cooked (a thing).
The -teros suffix meant roughly the same as -ward suffix in English or comparative. The one of a pair who has the quality manifested the most. Such as in decsteros "the one more to the right", u̯eiteros "the more far one", e̯enteros "the inner one".
The -istos suffix meant superlative. Thus, ğra̯uistos meant "heaviest", dlonghistos meant "longest", a̯ristos meant "of the best sort".
Another superlative suffix was -mmos/-immos/-ismmos/-tmmos as in e̯eĝhstmmos "outermost"
The -trom, -dhrom, -tlom, -dhlom suffixes meant instruments and tools. Thus a̯ero̯trom "plow", seddhlom "saddle", see̯tlom "sieve" etc.
The -ia̯/-a̯ suffixes meant collective number, abstract things and feminine gender. Thus preu̯ia̯ "mistress", neptia̯ "female nephew".
The -r/-n alternating stems belonged to the very ancient nouns, such as u̯odr "water" (gen. u̯edns, adj u̯odnos), u̯esr "spring" etc.
The -mn suffix meant neuter(non-animate) nouns, having certain properties. Such as a̯eĝmn "train", e̯neo̯mn "name", ĝneo̯mn "sign", see̯mn "seed".
The -kos suffix indicated material composition or origin. Such as in leukos "bright", a̯i̯uenkos "young".
The -ikos suffix meant "having to do with..."
The -iskos suffix indicated affiliation or place of origin.
The -ros was the default adjectival suffix as in a̯rĝros "shining"
The -tos suffix formed possessive adjectives (having X).
The -mos suffix produced action and event nouns such as in ğhermos "warmth, heat", sreumos "stream".
The -los was used for creating deminutives.
The -u̯ents suffix meant "rich in".
There were other suffixes as well.