Psalm 44/Notes/Lexical.V. 15.53532

The meaning of מָשָׁל: While typically associated with the wisdom sayings of the book of Proverbs (Prov 1:1, 6; 10:1; 25:1), the term מָשָׁל can have a more general sense of "saying" within a variety of genres (HALOT). The core meaning of "to be like, be equal to" appears to underly most uses of the nominal and verbal forms of the word (NIDOTTE, 2:1134). In contexts where the term clearly has a negative connotation, the most common modern English translation is "byword" (NIV, ESV, NRSV, NASB, NJB). Such translations suggest that the force of מָשָׁל is that of ridicule or taunting (see also CSB, NET, CEV, NCV). However, the core idea of comparison suggests that the true force of מָשָׁל is that of a negative example, presented to discourage others from doing likewise (Ibid, 2:1135).
The meaning of מְנוֹד־רֹאשׁ: This is the only occurrence in the HB of the nominal מְנוֹד. The verbal form נוּד, when applied to the "shaking of the head," is an idiomatic means of expressing concern; the exact nuance can range between sympathy, surprise, or scorn (NIDOTTE, 3:53). Given the parallelism with מָשָׁל (see previous note), the sense of מְנוֹד־רֹאשׁ in v. 15 could be that of disapproval or shock, as opposed to taunting or mockery.