Origins
The word 'notable' entered English in the fourteenth century from Old French 'notable,' descended from Latin 'notābilis,' meaning 'worthy of note' or 'remarkable.' The Latin adjective derives from 'notāre' (to mark, to observe, to note down), which comes from 'nota' (a mark, a sign, a distinguishing feature). The deeper etymology connects 'nota' to the PIE root *ǵneh₃- (to know), through the participial form *ǵneh₃-to-, which gave Latin 'nōtus' (known) and 'nota' (a mark by which something is known — a sign that enables recognition).
The PIE root *ǵneh₃- is one of the most fundamental verb roots in the language family, and its English derivatives span the entire spectrum from everyday words to technical vocabulary. Through the Germanic branch: 'know' (from Old English 'cnāwan'), 'knowledge,' 'acknowledge,' and 'ken' (Scottish/archaic English for 'to know'). Through Latin 'gnōscere/nōscere': 'cognition' (knowing together), 'recognize' (to know again), 'ignore' (not to know), 'noble' (well-known, hence illustrious), 'notion' (a thing known), and 'note/notable/notify/notorious/annotate.' Through Greek 'gignṓskein': 'gnosis' (knowledge), 'diagnosis' (knowing apart), 'prognosis' (knowing before), and 'agnostic' (not knowing).
The word 'notable' functions as both adjective and noun. As an adjective, it means 'worthy of attention': 'a notable achievement,' 'a notable exception,' 'a notable absence.' As a noun, it refers to a person of distinction: 'local notables,' 'notables of the community.' The noun usage was particularly important in French political history — the 'Assembly of Notables' (Assemblée des Notables) was a consultative assembly of prominent citizens convened by the French king, most famously in 1787, just before the Revolution.
Latin Roots
The distinction between 'notable' and 'notorious' is instructive. Both derive from the same root and both mean 'widely known,' but 'notable' is neutral to positive (known for achievement or importance) while 'notorious' is negative (known for wrongdoing or scandal). 'Notorious' comes from Medieval Latin 'notōrius' (well-known), from 'nōtōrium' (a thing commonly known). The semantic divergence shows how the same root — knowledge, being known — can split into praise and infamy depending on what one is known for.
The word 'noble' offers another branch from the same root. Latin 'nōbilis' meant 'knowable' or 'well-known,' and from there it shifted to 'famous,' 'illustrious,' and 'of high birth.' The assumption was that people of high birth were naturally well-known — visibility and social rank were inseparable in Roman society. English 'noble' thus means 'of recognized high quality,' whether applied to birth, character, metals (noble metals resist corrosion), or gases (noble gases resist chemical reaction).
In music, 'note' (from the same Latin 'nota,' a mark) refers to a written symbol representing a musical sound — a mark that encodes sonic information. Musical notation is literally a system of marks for making music 'knowable' on paper. The word thus bridges the worlds of knowledge and art, connecting the PIE concept of knowing to the medieval technology of writing music.