Melisma (Greek: μέλισμα, melisma, song, air, melody; from μέλος, melos, song, melody, plural: melismata) is the singing of a single syllable of text while moving between several different notes in succession. Music sung in this style is referred to as melismatic, as opposed to syllabic, in which each syllable of text is matched to a single note

https://en.wikipedia.org/wiki/Melisma

An A-minor natural scale under a slur

A slur is a symbol in Western musical notation indicating that the notes it embraces are to be played without separation (that is, with legato articulation). A slur is denoted with a curved line generally placed over the notes if the stems point downward, and under them if the stems point upward.

https://en.wikipedia.org/wiki/Slur_(music)