Our Gemara on Amud Aleph says 

רָבָא אָמַר אִם רָאִיתָ תַּלְמִיד שֶׁתַּלְמוּדוֹ קָשֶׁה עָלָיו כַּבַּרְזֶל בִּשְׁבִיל רַבּוֹ שֶׁאֵינוֹ מַסְבִּיר לוֹ פָּנִים שֶׁנֶּאֱמַר וְהוּא לֹא פָנִים קִלְקַל

⁦Rava said: If you see a student whose studies are as difficult for him as iron, this is due to his teacher, who does not show him a friendly countenance, but is overly strict with him. This practice inhibits the student’s learning, as it is stated: “And it has not whetted the surface [panim]” (Ecclesiastes 10:10). As explained previously, panim can also mean countenance.

Let us reflect on the term, “sever panim”, and it’s precise meaning. Sever is Aramaic for thinking about with the connotation of planning. An example of this comes from Daniel 7:25, as it describes the fiendish ruler who will arise in pre-messianic times.

וּמִלִּ֗ין לְצַ֤ד (עליא) [עִלָּאָה֙] יְמַלִּ֔ל וּלְקַדִּישֵׁ֥י עֶלְיוֹנִ֖ין יְבַלֵּ֑א וְיִסְבַּ֗ר לְהַשְׁנָיָה֙ זִמְנִ֣ין וְדָ֔ת וְיִתְיַהֲב֣וּן בִּידֵ֔הּ עַד־עִדָּ֥ן וְעִדָּנִ֖ין וּפְלַ֥ג עִדָּֽן׃

⁦He will speak words against the Most High, and will harass the holy ones of the Most High. He will think of changing times and laws, and they will be delivered into his power for a time, times, and half a time.

Rashi translates Veyisbar as ידמה בלבו, he will think in his heart. 

In the recent parasha, we find Yaakov noting that Lavan’s face was not the same as days prior (Bereishis 31:2). 

וַיַּ֥רְא יַעֲקֹ֖ב אֶת־פְּנֵ֣י לָבָ֑ן וְהִנֵּ֥ה אֵינֶ֛נּוּ עִמּ֖וֹ כִּתְמ֥וֹל שִׁלְשֽׁוֹם

Notably, Onkelos translates it as “svar apei”. Onkelos does not just say the Aramaic word for face, apei, which would then be a one to one translation of the verses word, “penei”. By adding the word “svar”, he is adding a layer of meaning. It is the thoughts, in this case negative sentiment, that comes forward and is projected on Lavan’s face. This is also consistent with Radak (Loc. Cit.)

We are beginning to see the word sever panim implies a thinking about, that shows on the face. The word sever itself is more than just thinking, it’s contemplating. In Nechemia (2:13) we see the usage clearly in this context, though it is spelled with the letter sin, not a samakh, and it is not uncommon for consonants to switch to ones with similar sounds in Aramaic to Hebrew, or even within both languages:

וָאֱהִ֨י שֹׂבֵ֜ר בְּחוֹמֹ֤ת יְרוּשָׁלַ֙͏ִם֙ אֲשֶׁר־[הֵ֣ם ׀ פְּרוּצִ֔ים] (המפרוצים) וּשְׁעָרֶ֖יהָ אֻכְּל֥וּ בָאֵֽשׁ׃

⁦and I surveyed the walls of Jerusalem that were breached, and its gates, consumed by fire.

Ibn Ezra (Loc. Cit.) has this precisely in mind:

⁦ואהי שובר And I surveyed - From "He will think (ויסבר) of changing" (Daniel 7:25). And from the language of the Sages of Blessed Memory: speculation (סברא). And the meaning is I was thinking about and studying the walls.

As an aside, by understanding that sover with a samakh and a sin are similar and can mean to contemplate, we can derive a deeper understanding of the famous discussion in Kiddushin 32b as to whether the elderly person in the verse (VaYikra 19:32) is actually an elderly person, a young sage, both, or either. The text in the Torah is:

 מִפְּנֵ֤י שֵׂיבָה֙ תָּק֔וּם וְהָדַרְתָּ֖ פְּנֵ֣י זָקֵ֑ן

Now what is the etymology of the Hebrew word seivah? It could mean white haired or perhaps because an older person is often more contemplative, maybe seivah is related to savir. Indeed Onkelos translates it as:

מִן קֳדָם דְּסַבַּר בְּאוֹרַיְתָא תְּקוּם

This could be an accident, or Onkelos enjoying the play on words, or a serious etymological point. The seivah is savir in Torah.

Let’s have some more fun by delving into the subtle meanings of l’shon kodesh. The word savir to think about or speculate is then also related to סבר to hope, because it is a positive and favorable speculation. So it is a speculation that is hopeful, and looking to see good things. 

Thus when Yaakov says (Bereishis 49:18), לִישׁוּעָֽתְךָ֖ קִוִּ֥יתִי , the Targum is לְפוּרְקָנָךְ סַבָּרִית:

Even the English word special comes from Latin species, that is something that appears. So the rebbe speculates, hopes and thinks positively about his Talmid, and this helps him succeed.

I will conclude with Hon Ashir’s inference from Shammai’s dictum in Avos (1:15):

וֶהֱוֵי מְקַבֵּל אֶת כָּל הָאָדָם בְּסֵבֶר פָּנִים יָפוֹת:

receive all men with a pleasant countenance.

Hon Ashir notes that it does not say Kol Odom “All men”, but literally Kol Ha-Odom “All of Man”. This implies that you must see the whole person through and through, conveying love, acceptance and optimism.