An interval smaller than a half step is called: A microtone.

Which terms refers to the overall shape of a melody?

the term referring to the overall shape of a Melody is. Contour.

Melodies may also be described by their melodic motion or the pitches or the intervals between pitches (predominantly conjunct or disjunct or with further restrictions), pitch range, tension and release, continuity and coherence, cadence, and shape.

What are melodic intervals?

A melodic interval is what you get when you play two notes separately in time, one after the other.

A half step, or semitone, is the smallest interval between notes in Western music.