In Spanish we have the verb sumergir, coming from Latin:
sum-mergo (subm-), si, sum, 3, v. a.,
I. to dip or plunge under, to sink, overwhelm, submerge, submerse.
Nonetheless, some related word such as inmersión and inmerso come from a similar Latin verb:
immergo (inm-), si, sum, 3 (
I. perf. sync. immersti, Plaut. Bacch. 4, 4, 26; acc. to the second conj., inf. pres. pass. immergeri, Col. 5, 9, 3), v. a. in-mergo, to dip, plunge, sink, or stick into any thing, to immerse (mostly poet. and in post-Aug. prose).
The definitions for both verbs are quite similar, but only the summergo verb reached the Spanish language as sumergir. There were attempts to stablish an inmergir verb but the Royal Spanish Academy stated that such verb was pointless in the Spanish language.
So, we have sumergir but not inmergir and I'm trying to understand why. I see in the definition for immergo that that verb was mostly used in poetry. So was it a cultured word and hence less used? Was in fact the verb summergo most used in Latin than immergo with the meaning of to dip, plunge or sink?