The word "ACTAG" is a five-letter term that is commonly used in the field of genetics. It refers to a sequence of nucleotides that make up a part of a DNA molecule. The correct spelling of this word is "ɛkˈtæɡ", as per the IPA phonetic transcription. The first two letters, "AC", represent the nitrogenous bases adenine and cytosine. The next three letters, "TAG", correspond to the bases thymine, adenine, and guanine, respectively. This sequence is essential in the process of DNA replication and transcription.