copper-bottomed

Completely safe investment

Copper-bottomed means completely reliable or guaranteed.

The term comes from the practice of sheathing ship hulls with copper to prevent decay and barnacle growth—a ship so protected was considered soundly built.

A copper-bottomed guarantee or copper-bottomed investment is one you can absolutely count on.

Chiefly British.

guaranteed

assured

Certain or self-possessed

ironcladImpossible to dispute
unquestionableCannot be challenged
foolproofIncapable of failure

watertight · certain · secure · infallible · undeniable · indubitable · unfailing · rock-solid · bombproof · fail-safe

nautical

sheathing

Protective outer layer

antifoulingMarine growth prevention
hullOuter covering or frame
shipbuildingConstructing maritime vessels

barnacles · cladding · corrosion-resistant · keel · frigate · man-of-war · galleon · shipyard · dockyard · naval

investment

gilt-edged

Of superior quality

blue-chipFinancially stable and reputable
securitiesTradeable financial assets
bondsTies that unite

government-backed · low-risk · treasury

idiom

flagship

Commander's principal vessel

scuttleSink intentionally; hurried shuffle
adriftFloating without control
awashFlooded or overwhelmed

unmoored · scuttlebutt · shipshape · all-hands

Opposites

reliability/trustworthiness

copper-bottomeduntrustworthy

Not deserving of confidence

unreliable · dubious · dodgy · questionable · suspect

certainty/risk

copper-bottomeduncertain

Not firmly known

risky · shaky · precarious · doubtful · iffy

risk/security

copper-bottomedrisky

Involving possible harm

precarious · speculative · hazardous · unsafe · high-risk

Family

bottom, copper, bottomless, buttocks, coppery, copperplate, coppersmith, copperware, coppersmithing

Familiarity: Top 1,000,000
Profile: Timeless · Concrete · Everyday, not technical · Rated G