Skeleton

Werdhom word conservation score = ★★★★

English: a skeleton, the skeleton

Dutch: een skelet, het skelet

German: ein Skelett, das Skelett

Danish: et skelet, skeletet

Norwegian: et skjelett, skjelettet

Swedish: ett skelett, skelettet

French: un squelette, le squelette

Spanish: un esqueleto, el esqueleto

Portuguese: um esqueleto, o esqueleto

Italian: uno scheletro, lo scheletro
Romanian: un schelet, scheletul

Polish: szkielet
Russian: скелет (skelet) 
Bulgarian: скелет (skelet) 

From Latin: sceletus, sceletī
From Ancient Greek: σκελετός (skeletós)

Note: the underlined languages have been reconstructed by academics, as there is no archaeological record of the language at that time.