Spianato
"Smoothed" – calm, even, and unaffected in performance.
What it means
Spianato is an Italian performance direction meaning literally "smoothed" or "leveled." It calls for a calm, even, unaffected delivery without strong dynamic or agogic swings.
The phrase canto spianato specifically denotes a simple, broadly flowing, "smoothed" melodic line that avoids exaggerated ornamentation.
Musical use
The term is best known from Chopin's Grande Polonaise brillante, preceded by an Andante spianato, whose calm, songful character forms a marked contrast with the brilliant, virtuosic polonaise that follows.
In general, spianato is used to mark passages that, despite possible technical demands, should convey a relaxed, flowing impression, without rough edges or conspicuous accents.
Spianato should be distinguished from semplice, which likewise implies simplicity but refers more to technical execution, whereas spianato especially emphasizes the smoothness and calm of the melodic line.
Performance practice
Play spianato passages with an even, flowing legato and avoid sudden dynamic leaps. Let the melody flow calmly, without interrupting it with too much rubato or accentuation.