Enter a clue or pattern or both:

### The Clue

Arithmetic series symbol (5 letter answer)

### The Answer

SIGMA

### Tags

### Notes

The answer SIGMA is uncommon, appearing about once every 375 puzzles.

### Related Clues

Ess

Millesecond

Millisecond

Calculus symbol

Frat letter

Fraternity letter

Greek letter

Greek "S"

Greek S

Start for Sophocles

Sum symbol

Summation symbol

" . . . sweetheart of ___ Chi"

"The Sweetheart of ___ Chi"

Symbol of conductivity

Tau's predecessor

___ Alpha Epsilon fraternity

Between rho and tau

Head of ancient Sparta?

Science society ___ Xi

Standard deviation symbol

Summation signifier, in math

Summation symbol in math

Symbol in a Riemann sum

___ Society (super-high I.Q. group)

### Definition

SIGMA as a noun:

1. the 18th letter of the Greek alphabet