Most Devil Fruit names in this dictionary are built from real Japanese mimetic words — ideophones that already described a sound or a texture before Oda ever doubled them into a fruit name. Gomu Gomu no Mi is the odd one out: ゴム (rubber) is an ordinary borrowed noun with no mimetic history at all, so Luffy's fruit doesn't sound like a description of stretching so much as a child's sing-song repetition of a vocabulary word. That's exactly the register the origin scene captures. Vol. 1 p.25 isn't Luffy naming his own power — it's an unnamed adult explaining it to a crowd of shocked villagers after the fact ("THAT WAS THE GUM-GUM FRUIT!! IF YOU EAT IT, YOUR ENTIRE BODY BECOMES LIKE RUBBER!"), and a page later Luffy repeats the name back with the plain pride of a kid who's just learned a cool new word for what happened to him ("I'm glad I ate the Gum-Gum Devil Fruit... look at what I can do!").
VIZ's translation strategy is the most disciplined in this dictionary. Across the 50-plus volumes this corpus samples — well over 200 raw hits for ゴムゴム alone — "Gum-Gum" never wavers, and the doubled-root shape survives into essentially every named technique: Gum-Gum Pistol (Vol. 9, p.34; reused with a fresh translator's hand at Vol. 12, p.23, worded identically both times), Gum-Gum Gatling Gun (Vol. 20, p.21), Gum-Gum Finger Net (Vol. 20, p.34), Gum-Gum Fireworks (Vol. 32, p.42). Compare that to Buggy's Chop-Chop Fruit, whose SBS answer column calls it "Scatter-Scatter fruit" instead, or Robin's Flower-Flower Fruit, left un-translated as "Hana Hana no Mi" on a character-bio page — Gum-Gum is the control group that shows VIZ's house style working exactly as designed, one word, one whole series.
The one place that discipline visibly breaks is Gear Third's debut. Vol. 34 p.54 has Luffy mid-windup, and where the Japanese still reads the familiar ゴムゴムのォ～～～！！！, VIZ prints "GEAR... THREE!!!" — dropping the Gum-Gum prefix entirely for the first time in the corpus. It isn't a translation slip; it's a naming-system collision. Gear First/Second/Third is a new tier of terminology layered on top of the Gomu Gomu template rather than generated from it (nothing in 'Gear' echoes 'rubber' the way every other attack name does), and VIZ's choice at the exact moment that tier debuts shows the translators reaching for the newer brand name over the reduplicated one, even mid-panel. It's the same instinct that would later let a bystander marvel, plainly, that "THAT'S THE GUM-GUM FRUIT'S POWER!!" (Vol. 33, p.176) — the phrase still reads as a settled, familiar noun to everyone on the page, Gear terminology or not.