(1):

(n.) An exclamation to call attention or to encourage one.

(2):

(n.) A loud exclamation; a call to invite attention or to incite a person or an animal; a shout.

(3):

(v. i.) To cry out; to exclaim with a loud voice; to call to a person, as by the word halloo.

(4):

(v. t.) To chase with shouts or outcries.

(5):

(v. t.) To encourage with shouts.

(6):

(v. t.) To call or shout to; to hail.