hollo / hollow [ˈhɒlo:]
hollo – interj., n., & v. – interj. – 1. used to attract attention; 2. used as a call of encouragement or jubilation; n. – an exclamation or call of hollo; v. – 1. to call or cry hollo, to attract the attention of; 2. call encouragement to; 3. to utter loudly, holler
hollow – adj., adv., n., & v. – adj. – 1. having a hole or cavity inside, not solid throughout; 2. of sound – echoing; 2. empty, hungry; 4. without satisfaction, meaningless; 5. insincere, cynical, false; adv. – Informal completely; n. – 1. an empty place; 2. a valley, a basin; v. – make hollow, excavate