הכי

Contraction of הָא כִי (há khí).

הָכִי • (hakhí)

1. So, thus, in this manner.
   • a. 500 C.E., Babylonian Talmud. Sanhedrin, 109b:

     הכי אתני בינייהו

     Thus they stipulated between themselves.

• אִי הָכִי (í hakhí)
• אֲפִילוּ הָכִי (afilú hakhí)
• הָכִי הַשְׁתָּא (hakhí hashtá)
• הָכִי נַמִּי (hakhí namí)
• מִשּׁוּם הָכִי (mishúm hakhí)

• Jastrow, Marcus (1903), A Dictionary of the Targumim, the Talmud Babli and Yerushalmi, and the Midrashic Literature‎^[1], London, New York: Luzac & Co., G.P. Putnam's Sons, page 350

From הֲ־ (ha-, interrogative particle) +‎ כִּי (kí, “thus”).

הֲכִי • (hakhí)

1. Most, the most.

   היא הילדה הכי גבוהה בכיתה. ― hi hayaldá hakhí gvohá bakitá ― She is the tallest girl in the class.

   • 2016, Jessica Knoll, הנערה הכי בת־מזל בעולם [Luckiest Girl Alive], Kinneret, Zmora-Bitan, Dvir – Publishing House Ltd.:

• The adjective introduced by הֲכִי appears in the indefinite state, even though its subject is nearly always semantically definite.
• In more formal Hebrew, the superlative is more commonly expressed by using בְּיוֹתֵר (b'yotér), or without an explicit “most”.