Earnest
A surname that usually began as a nickname for someone known as serious, sincere, or steadfast.
The #4,452 most common surname in the United States (2010 Census) — about 1 in every 38,748 Americans shares it.
Etymology
This surname is most naturally explained from the Middle English and modern English word "earnest," meaning serious, sincere, or zealous. That word goes back through Old French and ultimately to a Germanic base connected with firmness or seriousness. In some cases, the surname may also reflect the use of "earnest" as a given-name style or as an Anglicized form influenced by continental names with a similar sense.
History
The name is English in form and would have arisen independently in more than one place as a descriptive byname. Nineteenth-century surname writers occasionally linked similar-looking names to words meaning "earnest" or "steadfast," though they did not always agree on details. In modern English-speaking countries, Earnest is also familiar because it overlaps with the common first name Ernest, which may have encouraged occasional confusion or interchange in records.
Origin
Regions
Variant spellings
Fun fact
Because it is identical in sound to the common given name Ernest in many accents, the surname has often been mistaken for a forename in historical records.
From the historical record
“emust = Dut. emsi\ The adj.ffr«rf, 'earnest,' is only Mod. Ger. FABER (Ger.-Lat.) Smith; Carpenter [Lat. faber]”
— Surnames of the United Kingdom: a concise etymological dictionary (2 vols in 1)