Acts 2:38 NASB Peter said to them, “Repent, and each of you be baptized in the name of Jesus Christ for the forgiveness of your sins; and you will receive the gift of the Holy Spirit.
Strong's G907
βαπτίζω baptízō, bap-tid'-zo; from a derivative of G911; to immerse, submerge; to make whelmed (i.e. fully wet); used only (in the New Testament) of ceremonial ablution, especially (technically) of the ordinance of Christian baptism:—Baptist, baptize, wash.
Thayer's Greek Lexicon
STRONGS NT 907: βαπτίζω
βαπτίζω; (imperfect ἐβαπτιζον); future βαπτίσω; 1 aorist ἐβάπτισα; passive (present βαπτίζομαι); imperfect ἐβαπτιζομην; perfect participle βεβαπτισμενος; 1 aorist ἐβαπτίσθην; 1 future βαπτισθήσομαι; 1 aorist middle ἐβαπτισαμην; (frequent. (?) from βάπτω, like βαλλίζω from βάλλω); here and there in Plato, Polybius, Diodorus, Strabo, Josephus, Plutarch, others.
I.
1. properly, to dip repeatedly, to immerge, submerge (of vessels sunk, Polybius 1, 51, 6; 8, 8, 4; of animals, Diodorus 1, 36).
2. to cleanse by dipping or submerging, to wash, to make clean with water; in the middle and the 1 aorist passive to wash oneself, bathe; so Mark 7:4 (where WH text ῥαντισωνται); Luke 11:38 (2 Kings 5:14 ἐβαπτίσατο ἐν τῷ Ιορδάνῃ, for טָבַל; Sir. 31:30 (Sir. 34:30; Judith 12:7).
3. metaphorically, to overwhelm, as ἰδιωτας ταῖς ἐισφοραις, Diodorus 1, 73; ὀφλημασι, Plutarch, Galba 21; τῇ συμφορά βεβαπτισμενος, Heliodorus Aeth. 2, 3; and alone, to inflict great and abounding calamities on one: ἐβαπτισαν τήν πόλιν, Josephus, b. j. 4, 3, 3; ἡ ἀνομία με βαπτίζει, Isaiah 21:4 the Sept. hence, βαπτίζεσθαι βάπτισμα (cf. Winers Grammar, 225 (211); (Buttmann, 148 (129)); cf. λούεσθαι τό λουτρόν, Aelian de nat. an. 3, 42), to be overwhelmed with calamities, of those who must bear them, Matthew 20:22f Rec.; Mark 10:38; Luke 12:50 (cf. the German etwasauszubadenhaben, and the use of the word e. g. respecting those who cross a river with difficulty, ἕως τῶν μαστῶν οἱ πεζοί βαπτιζόμενοι διέβαινον, Polybius 3, 72, 4; (for examples see Sophocles' Lexicon under the word; also T. J. Conant, βαπτίζειν, its meaning and use, N. Y. 1864 (printed also as an Appendix to their revised version of the Gospel of Matthew by the American Bible Union); and especially four works by J. W. Dale entitled Classic, Judaic, Johannic, Christic, Baptism, Phil. 1867ff; D. B. Ford, Studies on the Bapt. Quest. (including a review of Dr. Dale's works), Bost. 1879)).
II. In the N. T. it is used particularly of the rite of sacred ablution, first instituted by John the Baptist, afterward by Christ's command received by Christians and adjusted to the contents and nature of their religion (see βάπτισμα, 3), viz., an immersion in water, performed as a sign of the removal of sin, and administered to those who, impelled by a desire for salvation, sought admission to the benefits of the Messiah's kingdom; (for patristic references respecting the mode, ministrant, subjects, etc. of the rite, cf. Sophocles Lexicon, under the word; Dict. of Chris. Antiq. under the word Baptism).
a. The word is used absolutely, to administer the rite of ablution, to baptize (Vulg.baptizo; Tertulliantingo,tinguo (cf.metgiro, de corona mil. § 3)): Mark 1:4; John 1:25f, 28; John 3:22f, 26; John 4:2; John 10:40; 1 Corinthians 1:17; with the cognate noun τό βάπτισμα, Acts 19:4; ὁ βαπτίζων substantively equivalent to ὁ βαπτιστής, Mark 6:14 (24 T Tr WH). τινα, John 4:1; Acts 8:38; 1 Corinthians 1:14, 16. Passive to be baptized: Matthew 3:13f, 16; Mark 16:16; Luke 3:21; Acts 2:41; Acts 8:12, 13,(Acts 8:36); Acts 10:47; 16:15; 1 Corinthians 1:15 L T Tr WH; 1 Cor 10:2 L T Tr marginal reading. WH marginal reading. Passive in a reflexive sense (i. e. middle, cf. Winers Grammar, § 38, 3), to allow oneself to be initiated by baptism, to receive baptism: Luke (Luke 3:7,12); Luke 7:30; Acts 2:38; Acts 9:18; Acts 16:33; Acts 18:8; with the cognate noun τό βάπτισμα added, Luke 7:29; 1 aorist middle, 1 Corinthians 10:2 (L T Tr marginal reading WH marginal reading ἐβαπτίσθησαν (cf. Winer's Grammar, § 38, 4 b.)); Acts 22:16. followed by a dative of the thing with which baptism is performed, ὕδατι, see bb. below.
b. with prepositions; aa. εἰς, to mark the element into which the immersion is made: εἰς τόν Ιορδάνην, Mark 1:9. to mark the end: εἰς μετάνοιαν, to bind one to repentance, Matthew 3:11; εἰς τό Ἰωάννου βάπτισμα, to bind to the duties imposed by John's baptism, Acts 19:3 (cf. Winer's Grammar, 397 (371)); εἰς ὄνομα τίνος, to profess the name (see ὄνομα, 2) of one whose follower we become, Matthew 28:19; Acts 8:16; Acts 19:5; 1 Corinthians 1:13, 15; εἰς ἄφεσιν ἁμαρτιῶν, to obtain the forgiveness of sins, Acts 2:38; εἰς τόν Μωυσῆν, to follow Moses as a leader, 1 Corinthians 10:2. to indicate the effect: εἰς ἕν σῶμα, to unite together into one body by baptism, 1 Corinthians 12:13; εἰς Χριστόν, εἰς τόν θάνατον αὐτοῦ, to bring by baptism into fellowship with Christ, into fellowship in his death, by which fellowship we have died to sin, Galatians 3:27; Romans 6:3 (cf. Meyer on the latter passive, Ellicott on the former). bb. ἐν, with the dative of the thing in which one is immersed: ἐν τῷ Ιορδάνῃ, Mark 1:5; ἐν τῷ ὕδατι, John 1:31 (L T Tr WH ἐν ὕδατι, but compare Meyer at the passage (who makes the article deictic)). of the thing used in baptizing: ἐν ὕδατι, Matthew 3:11; Mark 1:8 (T WH Tr marginal reading omit; Tr text brackets ἐν); John 1:26, 33; cf. Buttmann, § 133, 19; (cf. Winers Grammar, 412 (384); see ἐν, I. 5 d. α.); with the simple dative, ὕδατι, Luke 3:16; Acts 1:5; Acts 11:16. ἐν πνεύματι ἁγίῳ, to imbue richly with the Holy Spirit (just as its large bestowment is called an outpouring): Matthew 3:11; Mark 1:8 (L Tr brackets ἐν); Luke 3:16; John 1:33; Acts 1:5; Acts 11:16; with the addition καί πυρί to overwhelm with fire (those who do not repent), i. e. to subject them to the terrible penalties of hell, Matthew 3:11. ἐν ὀνόματι τοῦ κυρίου, by the authority of the Lord, Acts 10:48. cc. Passive ἐπί (L Tr WH ἐν) τῷ ὀνόματι Ἰησοῦ Χριστοῦ, relying on the name of Jesus Christ, i. e. reposing one's hope on him, Acts 2:38. dd. ὑπέρ τῶν νεκρῶν on behalf of the dead, i. e. to promote their eternal salvation by undergoing baptism in their stead, 1 Corinthians 15:29; cf. (Winers Grammar, 175 (165); 279 (262); 382 (358); Meyer (or Beet) at the passage); especially Neander at the passage; Rückert, Progr. on the passage, Jen. 18 47; Paret in Ewald's Jahrb. d. Biblical Wissensch. ix., p. 247; (cf. B. D. under the word Baptism XII. Alex.'s Kitto ibid. VI.).
So the Greek word meaning to completely plunge under the water, like a sinking ship or washing a dish, is translated as 'baptize' in the following Bible verses:
Matthew 3:6, 3:11, 3:13, 3:14, 3:16, 28:18
Mark 1:4, 1:5, 1:8, 1:9, 6:14, 6:24, 10:38, 10:39, 16:16
Luke 3:7, 3:12, 3:16, 3:21, 7:29, 7:30, 11:38, 12:50
John 1:25, 1:26, 1:28, 1:31, 1:33, 3:22, 3:23, 3:26, 4:1, 4:2, 10:40
Acts 1:5, 2:38, 2:41, 8:12, 8:13, 8:16, 8:36, 8:38, 9:18, 10:47, 10:48, 11:16, 16:15, 16:33, 18:8, 19:3, 19:4, 19:5, 22:16
Romans 6:3
1 Corinthians 1:13, 1:14, 1:15, 1:16, 1:17, 10:2, 12:13, 15:29
Galatians 3:27
If God said 'dunk/plunge/immerse' so many times, I lean towards the position that He meant it. There are other words for 'pour' that could have been used, but the Bible chose a word that means to plunge under water.