the.com/principal

The one who signs your detention slip and the budget, same pen.

means The person or thing that's first in rank, or the main sum of money before interest piles on top of it.

from From Latin 'principalis,' meaning 'first in importance,' built from 'princeps' — 'first one' or 'chief' (literally 'one who takes first,' from 'primus' plus 'capere,' to take or seize). The same root gave us 'prince.' The money sense and the school-authority sense both ride on this one idea of being first: the principal sum is the original amount before interest, and a school principal was originally the 'principal teacher' — the phrase got clipped, leaving just the adjective doing a noun's job.

spelling trick
principal is your pal, remember the A
finance twin
same word means the loan amount, not interest
legal sense
also means the main party in a crime or deal
old meaning
once just meant chief or most important thing
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