The Spanish verb 'conocer' (to know) comes from the Latin verb 'cognoscere' meaning 'to become acquainted with.' The Latin 'cognoscere' itself was formed by combining two elements: the prefix 'cum-' meaning 'together, with' and the verb 'gnoscere' meaning 'to know.' When these elements merged, the 'cum-' prefix evolved into 'co-', and over time, as Latin evolved into Spanish, 'cognoscere' transformed into the modern Spanish 'conocer.'

It's worth noting that 'conocer' in Spanish is specifically used for knowing people, places, or things in the sense of being familiar with them or having met them, rather than knowing facts or information (which uses 'saber'). This meaning aligns well with its Latin ancestor 'cognoscere' which emphasized the idea of becoming acquainted with something.

Several common Spanish words share their roots with 'conocer': 'reconocer' (to recognize) adds the prefix 're-' to mean 'to know again'; 'conocido' (acquaintance) is the past participle used as a noun; and 'conocimiento' (knowledge) is a noun derived from the same root.

English has many cognates sharing the same ancient root as 'conocer.' The word 'cognition' (the mental process of acquiring knowledge) comes from the same Latin 'cognoscere.' Other related English words include 'recognize' (which parallels Spanish 'reconocer'), 'cognizant' (aware or knowledgeable), and even 'noble' (which originally meant 'well-known' or 'notable'). The 'gn-' root relating to knowledge can also be seen in English words like 'ignore' (to not know) and 'diagnosis' (determining something through knowledge).