The article concerns the influence of humanist scholarship on sixteenth-century etymological practices, testified in the Neo-Latin reference works and special treatises on linguistics and history. Being an important part of historical research, which relied mostly on Greek and Latin literary sources, etymology could not but adopt some important principles and instruments of contemporary philological work, notably on the source criticism. The foremost rule was to study the sources in their original language, form, and eliminate any corrupted data as well as any information not attested in written sources. This presumed that every text had its own written history, which tended to be a gradual deterioration of its state, represented in the manuscript tradition that was subject to scribal errors and misinterpretations. This view on the textual history was strikingly consonant with that on the history of languages, which was treated by the humanists as permanent corruption and inevitable degeneration from the noble and perfect state of their ancient ancestors. In an effort to restore the original text, philology used emendation as a cure for scribal abuse and textual losses; likewise, language historians had their own tool, namely etymology, to reconstruct and explain the original form of words (including the nomenclature of various sciences). The intersection of both procedures is taken into account in the article and it demonstrates how textual conjectures, manuscript collation, and graphical interpretation of misreadings were employed by the sixteenth-century scholars to corroborate their etymological speculations, which established themselves as one of the ways of the reception and criticism of classical scholarly heritage.