ɪn ɐ dʒˈɛnɚɹəl kəmpjˈuːɾɪŋ sˈɛns, ˌoʊvɚlˈeɪɪŋ mˈiːnz "ðə pɹˈɑːsɛs ʌv tɹænsfˈɜːɹɪŋ ɐ blˈɑːk ʌv pɹˈoʊɡɹæm kˈoʊd ɔːɹ ˈʌðɚ dˈeɪɾə ˌɪntʊ mˈeɪn mˈɛmɚɹi, ɹᵻplˈeɪsɪŋ wʌt ɪz ɔːlɹˌɛdi stˈoːɹd".
In a general computing sense, overlaying means "the process of transferring a block of program code or other data into main memory, replacing what is already stored".