2. (noun) valley, basin, dale.
Ko Taui tētahi reo i roto i te matua, nō te mea ko ia tētahi tangata whānui te mōhio ki tērā takiwā tae atu ki te riu o Waikato (M 2006:124). / Taui was one of the commanders in the force because he was a person with broad knowledge of that district including the Waikato basin.
3. (noun) belly, chest, abdomen, stomach.
Kātahi ka haehaea taua ika nei he kai mā rātou, pāwharatia tonutia ai te riu, takoto kē atu, takoto kē mai (KO 15/10/1887:6). / Then that fish was cut up as food for them, the belly was ripped apart and lay open.
4. (noun) core (of the body).
Ko te riu te wāhanga waenga o te tinana, ko mua, ko muri, ko ngā taha hoki. Ko ngā uaua o te riu hei whakamārō i te katoa o te tinana, tae atu ki te tū me te neke a te tangata (RMR 2017). / The riu is the mid-section of the body, including front, back and sides. The core muscles stabilise the whole body, and allow it to both stand and move (RMR 2017).