The word "Antigen Ki" is spelled using the International Phonetic Alphabet (IPA) as /æn.tɪ.dʒən ki/. The "an" is pronounced as /æn/ and the "ti" as /tɪ/. The "dje" sound in "antigen" is represented by the IPA symbol /dʒ/. The "g" in "antigen" is a voiced velar consonant, pronounced as /ɡ/. The "ki" at the end is pronounced as /ki/. Overall, the word "antigen ki" refers to a substance that stimulates the production of antibodies in the body's immune system.