As with any kind of knowledge, information about word origins varies from speaker to speaker and affects language use accordingly. Clearly, one does not have to know anything about the etymology of the words in one’s native language in order to have an adequate command of the language. However, in speaking with an interlocutor who uses etymological data implicitly in order to convey a meaning––principally, in puns or other species of paronomasia––one is at a disadvantage in fully understanding an utterance that utilizes paronomasia without sharing the knowledge that underlies such word play.

The lack of etymological knowledge may also lead to erroneous word use. A typical contemporary case in both British and American English is that of the phrase “begging the question,” which is a direct translation of Latin petitio principii and is a type of fallacy in which an implicit premiss would directly entail the conclusion (i. e., basing a conclusion on an assumption that is as much in need of proof or demonstration as the conclusion itself). Speakers and writers ignorant of the phrase’s origin use it more and more frequently as a substitute for “raising the question,” and some usage manuals now recognize this erroneous meaning as acceptable.

Knowledge of a word’s origin and meaning field can also serve to heighten one’s sense of the semantic implications of the word. A good case in point is filibuster, which was notoriously in the news a few weeks ago in connection with a certain U. S. senator’s legislative shenanigans. Here is the word’s etymology, as cited from The Oxford English Dictionary Online:

Etymology: The ultimate source is certainly the Dutch vrijbuiter in Kilian vrij-bueter (see freebooter n.). It is not clear whether the 16th cent. English form flibutor, of which we have only one example, was taken from Dutch directly or through some foreign language. Late in the 18th cent. the French form flibustier was adopted into English, and continued to be used, with occasional variations of spelling, until after the middle of the nineteenth century. About 1850–54, the form filibuster, < Spanish filibustero, began to be employed as the designation of certain adventurers who at that time were active in the W. Indies and Central America; and this has now superseded the earlier flibustier even with reference to the history of the 17th cent.

The derivation of filibuster from freebooter ‘originally: a privateer. Later more generally: a piratical adventurer, a pirate; any person who goes about in search of plunder. Also fig. and in extended use’ only serves to aggrandize the meaning:

Etymology: < Dutch vrijbuiter privateer, pirate, robber (1572) < vrijbuit prize, spoils, plunder (1575; chiefly in the phrase op vrijbuit varen to go capturing ships or plundering, op vrijbuit gaan , and variants;< vrij free adj. + buit booty n.; compare Middle Low German vrībǖte (> Swedish fribyte (1561)), German Freibeute (1571 as freye peuth , or earlier)) + -er -er suffix. Compare Middle Low German vrībǖter (> Swedish fribytare (1559)), German Freibeuter (1569 as fribuiter, or earlier); also Middle French vributeur, vributer (1582;< Dutch), all in sense ‘privateer, pirate’. Compare filibuster n.

The original meanings of both filibuster and freebooter are now lost to most speakers of English. A pity, given that the behavior of ‘one who practices obstruction in a legislative assembly’ can and should be evaluated in the light of the words’ etymology.