sell out

verb

1. Also (chiefly Brit): sell up. to dispose of (supplies of something) completely by selling

2. informal,  (tr) to betray, esp through a secret agreement

3. informal,  (intr) to abandon one's principles, standards, etc

noun

1. informal,  a performance for which all tickets are sold

2. a commercial success

3. informal,  a betrayal

4. informal,  a person who betrays their principles, standards, friends, etc

Idioms and Phrases

Dispose of entirely by selling. For example, The rancher finally sold out to the oil company , or The tickets to the concert were sold out a month ago . [Late 1700s]

Betray one's cause or colleagues, as in He sold out to the other side . [ Slang ; late 1800s]