ken

One of the first words people often learn in Hebrew is ken כן - "yes". However, that meaning only began in the Middle Ages. In the Bible it appears frequently, but as an adverb with the more general sense of "so" or "thus". Klein provides two possible etymologies. One is that the word, and its Semitic cognates

probably derive from the Semitic demonstrative base *ka- . Compare כה, כי and אכן.

The other theory is that

according to some scholars כן derives from כון, hence literally means "established, confirmed" and is related to כן [second definition]

That second entry for ken is an adjective and means "right, truthful, honest". The root כון "set up, establish, be firm; prepare, ready; straighten, direct", and its related form כנן "regulate, adjust" provide us with many common Hebrew words:

• konan כונן - rack, computer disk drive (from "set up, established")
• konanit כוננית - shelf, book stand
• konanut כוננות - preparedness
• hachana הכנה - preparation
• muchan מוכן - ready
• mechina מכינה - preparatory class, school
• nachon נכון - correct
• techuna תכונה - originally "arrangement", now "character"
• kavana כונה - intention (from "he directed")
• kivun כיוון - direction
• machon מכון - fixed place, later institute, institution
  

In the Bible we also find the word mechona מכונה meaning "base, stand". In the Haskala period the word mechona was used to mean "machine" - only due to its similar sound. From here, Itamar Ben-Avi (Ben-Yehuda's son) coined the term mechonit מכונית for "automobile" (originally agala mechonit עגלה מכונית - "mechanical carriage"). According to Kutscher here, monit מונית - "taxi" is also connected:

There is no end to innovations in the domain of technology. Understandably, few were founding ancient sources and the majority have been borrowed from foreign tongues. The Greek mekhane has been given a Hebrew garb in mekhona for “machine.” Hence mekhonit for “motor-car,” and, by dropping the “kh” we have monit, a taxi, which looks as if it were related to the root מנה (mnh – “to count”) and is thus closer to the original meaning of “taxi” (which, of course, is short for “taximeter”).

The word ken appears in a number of common words and phrases as well:

• בכן - if so, thus
• לכן - therefore
• שכן - because
• אחר-כן - afterwards
• אם כן - if so
• אלא אם כן - unless
• אף על פי כן - nevertheless
• על כן - therefore
• גם כן - also
• כמו-כן - likewise

While many of these phrases appear with these meanings in the Tanach, the last one - kmo khen - has a very different origin. Avshalom Kor in Higiya Zman Lashon writes that the origin of this phrase is from Yeshayahu 51:6 -

שְׂאוּ לַשָּׁמַיִם עֵינֵיכֶם וְהַבִּיטוּ אֶל-הָאָרֶץ מִתַּחַת, כִּי-שָׁמַיִם כֶּעָשָׁן נִמְלָחוּ וְהָאָרֶץ כַּבֶּגֶד תִּבְלֶה--וְיֹשְׁבֶיהָ, כְּמוֹ-כֵן יְמוּתוּן; וִישׁוּעָתִי לְעוֹלָם תִּהְיֶה, וְצִדְקָתִי לֹא תֵחָת.

The JPS translates it as:

Raise your eyes to the heavens,
And look upon the earth beneath:
Though the heavens should melt away like smoke,
And the earth wear out like a garment,
And its inhabitants die out as well,
My victory shall stand forever,
My triumph shall remain unbroken.

The phrase kmo khen yemutun is translated as "will die as well", where kmo khen means as we offered above "as well". But Kor points out that the singular of kinim כינים - "lice" is ken כן - "louse", just as the singular of izim עיזים - "goats" is ez עז -"goat" (another example is ניסים nissim - "miracles", and nes נס.) While we are more familiar with the singular form kina כינה, Kor writes that it is only the feminine of ken (as iza עיזה is the feminine of ez).

He writes that the structure of the verse indicates that a better translation would be "die like a louse", because the previous two examples were "melt away like smoke" and "wear out like a garment". To die "as well" doesn't make sense in the context.

While we do find kmo and ken connected (but not adjacent) in the Tanach - Mishlei 23:7 - this is a nice way of showing how our initial assumption of the meaning of the phrase can be affected by its more common use. Or maybe we just don't like to think about lice...