Here we have a description of the 6 month fetus of John the Baptist meeting the newly conceived Christ child.
And it came to pass, that, when Elisabeth heard the salutation of Mary, the babe leaped in her womb; and Elisabeth was filled with the Holy Ghost:
"leaped" [in her womb]
Akin to σκαίρω skairō (to skip); to jump, that is, sympathetically move (as the quickening of a fetus): - leap (for joy).
This leap of the unborn fetus is described as a move which denotes the quickening [of life] and a leap for joy at the meeting with the Christ child, and accompanied by an indwelling of the Holy Spirit.
Here, too, we see the same in Mary's spirit, as a born again spirit quickening and leaping for joy at the discernment of that holy thing growing within her--and as the increase of her soul as it magnifies the Lord.
47And my spirit hath rejoiced in God my Saviour.
From ἄγαν agan (much) and G242; properly to jump for joy, that is, exult: - be (exceeding) glad, with exceeding joy, rejoice (greatly).