Schietto
"Simple, plain" – a performance direction calling for playing without ornamentation.
What it means
Schietto is an Italian performance direction meaning 'simple' or 'plain.' It calls for a straightforward, unadorned delivery, avoiding added ornaments, pronounced rubato, or exaggerated expression.
The related form schiettamente carries the same meaning as an adverb and is likewise used to characterize a melodic line or passage more precisely.
Musical use
Composers usually mark a passage schietto where a melody should deliberately return to a clear, plain line after a more expressive or freer section, or where a folk-like, unpretentious tone is wanted from the outset.
Schietto should be distinguished from semplice, which means something similar but points more toward technical simplicity of execution, whereas schietto more strongly emphasizes a character of being 'unadorned, direct.'
Performance practice
When you see schietto, deliberately avoid ornaments, exaggerated rubato, or sweeping dynamic arcs. Play the melody plainly and directly, as though simply telling it, without dressing it up.