Tempo del comincio – Time of I begin – same tempo as at start
sempre marcatissimo – always marked – always very accentuatedly
How curious: there’s only one work from my performing life that leaps to mind where the first instruction has a very prominent place (and the only place I’ve ever encountered it), and the rest of the score is littered with the second, and that’s Tchaikovsky’s Second concerto for piano op.44. The ‘tempo del comincio’ marks the start (b. 394) to the first treatment of the first subject and, again (b.479), at the start to the final onslaught in the cadenza, as you prepare to rejoin the orchestra.
(It sticks in the mind because a simple Tempo Primo would have done just fine, but Tchaikovsky, like e.g. Alkan, sometimes likes to do his italian the hard (and obscure) way for no apparent good reason. Incidentally, he also demands no fewer than 12 ‘p’s and 9 ‘f’s dynamically from you: quite as memorably odd. <g>)
Curiouser and curiouser, as Alice once said… 🙂
If they’re musical terms, I would guess “same tempo as the beginning” and “always use strong marcato”