"At any rate, your claim that the terms used are all the same appears to be, let's say, not true,"
Luk 1:24, 31, 36 the word conceive used is sullambanw (sullambano)
Mary: Luke 1:31 "And, behold, thou shalt conceive in thy womb, and bring forth a son, and shalt call his name JESUS."
Elizabeth: Luke 1:24, "And after those days his wife Elisabeth conceived, and hid herself five months, saying,"
Luke 1:36, "And, behold, thy cousin Elisabeth, she hath also conceived a son in her old age: and this is the sixth month with her, who was called barren."
"In the case of Elizabeth, the term actually means carnal (lustful) conception."
It's the same word, sullambanw (sullambano), used to describe Mary's condition.
That seems to be Luke's preference. Matthew and Paul use different words. You and xzins implied that all three use the same word. Lue's choice is indeterminete. Matthew's and Paul's is very specific. But they are not the same words.