Here we have a description of the 6 month fetus of John the Baptist meeting the newly conceived Christ child.
Luke 1:41
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]
G4640
σκιρτάω
skirtaō
skeer-tah'-o
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.
--Luke 1
"hath rejoiced"
G21
ἀγαλλιάω
agalliaō
ag-al-lee-ah'-o
From ἄγαν agan (much) and G242; properly to jump for joy, that is, exult: - be (exceeding) glad, with exceeding joy, rejoice (greatly).