@variablepulserate Cello is somewhat similar to bass viol, though sounds completely different, but the whole viol family is huge — and the modern double bass is the last surviving member of the viol family for a typical Western classical orchestra. Evidence is in the standard guitar-like tuning of fourths (versus fifths for the violin family), the underhand ("German") bow hold, the viol-style shoulders (though many basses now have a cello-like shape), and the flat back (the violin family has an arched back).
The naming convention can be confusing but it helps to note that "viol" is synonymous with "viola da gamba" ("leg viol"). The "-in" ending for "violin" is a diminutive, so literally "small viola".
"Cello" is itself a very confusingly shortened diminutive: "violone" ("viol" + "one" -> "big viol") -> "violoncello" ("small big viol") -> "cello".