In ancient times, Greek had a letter "Ϝ" called digamma that disappeared and that had the sound of an English "v" or "w".
Ϝ ϝ Ϛ ς
The Greek digamma corresponds to the English "F" and had an "f" or "v" or "w". As it was not needed for sound value, it disappeared except for it's numeric value of six (6).
Here are some Greek words that originally had a "
digamma".
see: «ϝείδε» (vee-the or we-the) became «είδε» (ee-tha) and is related, through Latin, to the English "video".
house: «ϝοικος» (vee-kos or wee-kos) became «οίκος» (ee-kos) and is related to the Old English "wic" or house.
work: «ϝέργα» (ver-ga or wer-ga) became «έργα» (er-ga) and is related to the German "Werk" and English "work".
Some of these (and other) words are detailed below.
Σ σ ς
Unlike the upper case sigma "
Σ", the lower case sigma is written differently if it is at the end of a word, as "
ς" or not at the end of a word as "
σ".
ΧΡΙΣΤΌΣ = χριστός
Hebrew has a number of such letters. Greek has only this one.