#3: Helpful information if one is using Latin, but this isn't the forum for that. 😉
Interesting, though, is that English (at least AE) does use "emeriti" for the plural form of the noun and the adjective.
"emer·i·tus | \ i-ˈmer-ə-təs
plural emeriti\ i-ˈmer-ə-ˌtī
Definition of emeritus
(Entry 1 of 2)
: a person retired from professional life but permitted to retain as an honorary title the rank of the last office held
Definition of emeritus (Entry 2 of 2)
1 : holding after retirement an honorary title corresponding to that held last during active service
2 : retired from an office or position
—converted to emeriti after a plural
However, some (but definitely not all) AE speakers do differentiate between "alumnus" and "alumna" and "alumni" (male-only or mixed gender) and "alumnae" (female only).
Also from M-W:
Alumnus or Alumna?
"Many people are comfortable using the word alumni to refer to someone who was a student of a particular school. However, others feel quite strongly that this is an error and that the following forms should be used: alumnus (for one male), alumni (for multiple males, or for a mix of males and females), alumna (for one female), and alumnae (for multiple females). The shortened form alum and its plural form alums began to be used in the 19th century. Initially, alum was widely viewed as highly colloquial or informal, but is increasing in use as a gender-neutral alternative."