the word submerge is a direct borrowing from latin submergere, itself a compound of the prefix sub- ('under') and the verb mergere ('to dip, plunge'). mergere originates from the proto-indo-european root mezg-, meaning 'to dip, plunge', which also gave rise to related english words like 'merge' and 'emerge'. the literal sense of 'plunging under' has been retained in modern english, describing the action of going beneath a liquid's surface, while also extending metaphorically to mean being overwhelmed or concealed.

Structure: sub (under) + merge (dip, sink) sub- is a prefix from latin, meaning 'under, below'. merge is from latin mergere, meaning 'to dip, immerse, sink'.