When Jesus spoke of God, he often said Father, or Lord. Or at least he used the corresponding words in the language of his time. Of course, these words have an ordinary meaning, besides designing the deity. But it also happens that Jesus say God (Dieu, in French). For instance in Mat 22:21 So, give back ... to God what is God's. However the etymology of words such that god or dieu is not biblical. For instance, the french word comes from (as I was told) the greek god Zeus ! I presume that the word god must likewise come from Germanic mythology. In arab countries, the equivalent is Allah, even for Christians. The general rule is that we use the common name for a deity, but with an upper case initial, to mark that God is unique. But God, or Dieu, is by no means God's name.
So, which word did Jesus employ, when He spoke of "God" ?
Certainly, Jesus did not pronounce the tetragram, which had not been in use for several centuries. The only clue that I found is in Mat 27:46, where Jesus says Eli, Eli, lama sabachthani ? I doubt however that this gives the answer to my question: the name Eli must not have been common at that time, since in the next verse, some in the crowd misunderstand, thinking that He calls the prophet Elias. After all, Jesus is citing Ps 22:2, in the original Hebrew, a language that was not any more in use.