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- (Thiruvananthapuram) Oruvadālkotta
- (Thiruvananthapuram) Onivāram
- (Thiruvananthapuram) Ottūr
- (Thiruvananthapuram) Onampalli
- (Thiruvananthapuram) Oranallūr
- (Kollam) Orkkod
- (Ernākulam) Oravanturutu
- (Ernākulam) Ochanthururtha
- (Ernākulam) Onakkoor
- (Alappuzha) Olavipe
- (Malappuram) Ozhūr
- (Malappuram) Ozhur
- (Malappuram) Omachchapuzha
- (Kozhikode) Omassheri
- (Wayanad) Olagode
- (Kozhikode) Ollūr
- (Kannur) Olavilam
- (Kozhikode) Onchiyam
- (Kannur) Orikara
- (Kāsaragod District) Oyulat
- (Kāsaragod District) Ochathidle
- (Kāsaragod District) Odotadka
- (Wayanad) Olivayel
- (Thrissur District) Orumanayūr
- (Malappuram) Othalūr
- (Palakkad district) Othalūr
- (Palakkad district) Ommala
- (Wayanad) Ottapālam