Where does “direttissimo” come from?

direttissimo (Italian) comes from Italian diretto, from Latin dīrectus, from Latin dīrigō, from Latin dis-, from Latin calceus, from Latin calx, from Ancient Greek χάλιξ — small stone, pebble; gravel, rubble.

direttissimo (Italian): through train, express train (express, or non-stop)

Definitions

through train, express train (express, or non-stop)

Ancestry of “direttissimo”, step by step

Step	Language	Word	Meaning
1	Italian	diretto	direct, straight, immediate; addressed, intended;...
2	Latin	dīrectus	laid straight, arranged in lines, having been arranged in lines
3	Latin	dīrigō	to lay straight; arrange in lines (especially in military contexts)
4	Latin	dis-	asunder, apart, in two; reversal, removal;...
5	Latin	calceus	shoe
6	Latin	calx	limestone; chalk; the finish line
7	Ancient Greek	χάλιξ	small stone, pebble; gravel, rubble

Every word from Ancient Greek χάλιξ →Every word from Latin dis- →Every word from Latin calx →