One of the problems with memorizing vocabulary is that you feel like you memorize a word, and then you never get to use it. We are going to use a different approach to vocabulary lists.
Here is a list of the words that are used 3 times or more in Acts chapter 2. There are 59 of them.
There are considerably fewer "root words". But here I am giving you the words as they occur. So τῇ and τήν are treated as 2 of these 59 words, even though they are both forms of the root word (or lemma) of ὁ.
There are another 384 words that are used just once or twice in the chapter. We will not try memorizing any of those yet.
If you can get on top of the 59 most common words in this chapter, it will really help you in your sight-reading of the text.
Word Frequency Acts 2 Count Word as it
appears in
the textWordDescr Lemma Brief Definition 66 καί conjunction καί and 14 δέ conjunction δέ but/and 13 μου personal pronoun, genitive singular ἐγώ I 12 τόν definite article, accusative singular masculine ὁ the 11 ὁ definite article, nominative singular masculine ὁ the 11 τῆς definite article, genitive singular feminine ὁ the 11 τοῦ definite article, genitive singular masculine ὁ the 11 ἐπί preposition ἐπί upon 11 ἐν preposition ἐν in 9 οἱ definite article, nominative plural masculine ὁ the 9 τήν definite article, accusative singular feminine ὁ the 9 εἰς preposition εἰς into 9 τέ conjunction τέ (often translated) 8 αὐτοῦ personal pronoun, genitive singular masculine αὐτός self 8 τῇ definite article, dative singular feminine ὁ the 8 ὑμῶν personal pronoun, genitive plural σύ you 8 ὅτι conjunction ὅτι for 7 ἀπό preposition ἀπό from 7 θεός noun, nominative singular masculine θεός God 7 πάντες adjective, nominative plural masculine πᾶς all/each 6 διά preposition διά through 6 τοῦ definite article, genitive singular neuter ὁ the 6 τούς definite article, accusative plural masculine ὁ the 6 ἡ definite article, nominative singular feminine ὁ the 5 οὗ relative pronoun, genitive singular masculine ὅς who, that* 5 γάρ conjunction γάρ for 5 πρός preposition πρός to 5 ἦσαν verb, 3rd person imperfect active indicative plural εἰμί to be 5 πνεύματος noun, genitive singular neuter πνεῦμα spirit 5 ἐστί(ν) verb, 3rd person present active indicative singular εἰμί to be 4 οὖν conjunction οὖν therefore 4 τά definite article, accusative plural neuter ὁ the 4 ἡμέραν noun, accusative singular feminine ἡμέρα day 4 τό definite article, accusative singular neuter ὁ the 4 τό definite article, nominative singular neuter ὁ the 4 σου personal pronoun, genitive singular σύ you 4 ταῖς definite article, dative plural feminine ὁ the 4 θεοῦ noun, genitive singular masculine θεός God 4 κατά preposition κατά against, according to, in 4 ἄνδρες noun, vocative plural masculine ἀνήρ man 4 ἐκ preposition ἐκ from 3 κύριος noun, nominative singular masculine κύριος Lord 3 τάς definite article, accusative plural feminine ὁ the 3 ταύτης demonstrative pronoun, genitive singular feminine οὗτος this 3 ἕκαστος adjective, nominative singular masculine ἕκαστος each 3 κατοικοῦντες verb, present active participle nominative plural masculine κατοικέω to dwell 3 τῷ definite article, dative singular neuter ὁ the 3 ἁγίου adjective, genitive singular neuter ἅγιος holy 3 ἄν particle ἄν (often untranslated) 3 ὑμεῖς personal pronoun, nominative plural σύ you 3 αὐτῶν personal pronoun, genitive plural masculine αὐτός he/she/it 3 αὐτό adjective, accusative singular neuter αὐτός he/she/it 3 αὐτόν personal pronoun, accusative singular masculine αὐτός he/she/it 3 τοῦτο demonstrative pronoun, nominative singular neuter οὗτος this/that 3 αὐτοῖς personal pronoun, dative plural masculine αὐτός self 3 λέγει verb, 3rd person present active indicative singular λέγω to say 3 τῶν definite article, genitive plural masculine ὁ the 3 τοῦτον demonstrative pronoun, accusative singular masculine οὗτος this/that 3 Ἰησοῦν noun, accusative singular masculine Ἰησοῦς Jesus
*οὗ occurs in Acts 2:2 as an adverb meaning "where/in what place". You must use the context to know whether the adverb οὗ is intended, or the relative pronoun οὗ.
In English, we also have words that are different parts-of-speech, but are spelled the same way. For instance, "arm" can be a verb, as in:
The Ukranian government decided to arm many of its citizens in preparation for a Russian invasion.
It can also function as a noun, as in:
I got an insect bite on my arm, and now it itches.