From jmj(“(one) being in; interior”) + wrt. The identity and meaning of the second term are unclear. It is written identically to wrt(“great one”), but perhaps it is instead to be connected with wrt(“a kind of barque”).
Any attempt to determine the etymological meaning of the term should probably take it in conjunction with its antonym tꜣ wr(“larboard, port”); setting aside wr/wrt, here one can draw a contrast between jmj in the one term, referring to the interior of something, and tꜣ in the other term, apparently referring to the land exterior to the ship. For tꜣ, compare the etymology of the English term port; because the steering oar is generally found on the right (starboard) side of the ship, it is the left (port) side that moors facing the land. It is then easy to see how the starboard side could be perceived as the ‘interior’ of the vessel, facing away from land. (Alternatively, it may be the steering oar itself that is referred to as ‘being in’ / in the ‘interior’ of the vessel.)
Thus, the term as a whole has variously been interpreted as ‘that which is inside the barque’, or, taking wrt as ‘great one’ in reference to the ‘great oar’ (steering oar), ‘the one on the inside of the steering oar’. Servajean rejects the latter interpretation and prefers the former, as wrt is nowhere else attested to refer to the steering oar specifically.
“jm.j-wr.t (lemma ID 25350)”, “jm.j-wr.t (lemma ID 25360)”, and “jm.j-wr.t (lemma ID 450653)”, in Thesaurus Linguae Aegyptiae[1], Corpus issue 18, Web app version 2.1.5, Tonio Sebastian Richter & Daniel A. Werning by order of the Berlin-Brandenburgische Akademie der Wissenschaften and Hans-Werner Fischer-Elfert & Peter Dils by order of the Sächsische Akademie der Wissenschaften zu Leipzig, 2004–26 July 2023