-rô and -ro are masculine endings in Primitive Elvish which indicate agentival formations or just masculine endings.
Its feminine counterpart was -rî, -rê.
-rô was usually suffixed to a word root with or without n-infixion, and produce the word. The short form -ro is used after a suffixed stem-vowel; a possible exception to this was kwentro instead of *kwetro or *kwentrô. In a few cases, it seems to be suffixed to a verb stem.
The ending was frequently extended with -ondô, like lansrondo, kalro-ndo.
It is perhaps the masculine version of the adjectival ending -râ. Definitely it contains the simple masculine ending -ô, -o.
-rô was perhaps related to -nô, another coexisting agentival ending and the two were perhaps sometimes interchangeable, as seen with the alternate forms stabrô/stabnô.
In Quenya (and likely also in Telerin) -rô/-ro were to be seen as the ending(s) -ro/-r, since the final short vowels of Primitive Elvish were lost, and the long vowels were shortened.
In Sindarin things were a bit more complicated, as the final vowel was lost in all cases (apocope); this bought a final -r adjacent to a consonant (eg. tamrô > *taṃr) and as a reaction, a vowel evolved between them to make the word pronounceable, resulting thus in the ending -or (hence *taṃr > tavor).
In other cases, the extended form -rondô was preferred in the Sindarin branch, which allowed the word preserve the more distinct ending -ron.
- Abarô/Abaro (ABA) > Q. Avar S. Abóro > Avar
- beurô (BEW) > T. búro S. beor > byr
- kalrô (KAL) > Q. callo S. callon (from kalrondô)
- kwentro (KWET) > Q. quentaro S. pethron (*kwentrondô), pindor
- ndeuro (NDEW) > Q. neuro S. dior
- njadrô (NYAD) > Q. nyarro S. nâr
- onrô (ONO) > S. odhron (*onrondô)
- stabrô (STAB) > S. thavron (*stabrondô), thavon (from alt. stabnô)
- tamrô (TAM) > Q. tambaro S. tavor
- târo (TAȜ) > Q. tár, tar S. taur, tôr
- wanôrô (ONO) > Q. onóro, S. wanúro > gwanur
The Primitive words below are unattested but can be easily deduced by Quenya and Sindarin words. Note however that possibly most of these words did not exist in Primitive Elvish but would be coined later; eg. in early Quenya or early Sindarin.
- ataro (ATA) > Q. atar S. adar
- etledrô (LED) > S. etledro > edledhron
- kaprô (KAP) > S. cabor
- khatrô (KHAT) > S. hador or hadron (*khatrondô)
- lansrô (LAS) > S. lathron (lansrondô)
- makrô (MAK) > Q. macar S. magor
- mbadro (MBAD) > S. badhor or badhron (*mbadrondô)
- mbakhro (MBAKH) > S. bachor
- ndakrô (NDAK) > S. ndakro, dagor
- ñgolrô (ÑGOL) > S. gollor
- ok'taro (KOTH) > Q. ohtar
- telero (TELE) > Q/S. teler
Finally, there are some words whose forms suggest that their stem is verbal, not the sundocarme; ontâro is such a form (cf. onrô of the same root). Again, it's possible that the rest of the words were coined later, or formed by analogy, and did not exist in Primitive Elvish:
- ontâro (*ontâ- "to beget") > Q. ontar
- maktâro (maktâ- "to wield a weapon") > Q. mahtar S. maethor
- nektâro (*naktâ- "to slay") > Q. nehtar
- tambarô (tambâ- "to knock" ) > Q. tambaro
Words that do NOT contain -rô
Other agentive suffixes are