latin vs english plurals

[JOSEPH E. LAFERRIERE]

The person who initiated this conversation was apparently
not a native English speaker. I believe she or he was from
Brazil, unless I am mistaken. I am certain she or he was
seeking practical advice rather than a philosophical
debate.
   Remember that very few people in the United States have
ever studied Greek or Latin. Therefore, any Greek or Latin
word passing into use by the general public tends to lose
its declension. The general public uses the words "octopus,
cactus, coleus, index," etc. This is the reason the plurals
are frequently given as "octopuses, cactuses, coleuses, and
indexes" instead of "octopi (or octipides). cacti, colei,
and indices."  The words "data" and "bacteria" are also used
by the public, both often as singular words. However, the
word "taxon" is completely unknown to the public, as is "calyx."
Therefore, "taxa" and "calyces" continue to be used,
unpolluted by public usage.
   I hope this helps. In general, if a word is used by the public,
use the -s plural. If not, use the Greek or Latin.

--
Dr. Joseph E. Laferriere
"Computito ergo sum ...  I link therefore I am."