let out in WordNet English dictionary

1. make known to the public information that was previously known only to a few people or that was meant to be kept a secret
   "The auction house would not disclose the price at which the van Gogh had sold"; "The actress won't reveal how old she is"; "bring out the truth"; "he broke the news to her"; "unwrap the evidence in the murder case"
   unwrap  disclose  let on  bring out  reveal  discover  expose  divulge  break  give away  let out 
   
2. bring out of a specific state
   bring out  let out 
   
3. express audibly; utter sounds (not necessarily words)
   "She let out a big heavy sigh"; "He uttered strange sounds that nobody could understand"
   utter  emit  let out  let loose 
   
4. make (clothes) larger
   "Let out that dress--I gained a lot of weight"
   let out  widen 
   

let out in English Wiktionary