I. give‧a‧way¹ /ˈɡɪvəweɪ/ noun

1. [singular] something that makes it easy for you to guess something
be a clear/dead giveaway (=make it very easy to guess something)
He’d been smoking dope; his glazed eyes were a dead giveaway.

2. [countable] something that is given away free, especially something that a shop gives you when you buy a product

[TahlilGaran] Dictionary of Contemporary English ▲

II. giveaway² adjective [only before noun]
giveaway prices are extremely cheap

[TahlilGaran] Dictionary of Contemporary English ▲

giveaway
something that is given away free, an act of giving something away, an unintential betrayal of a secret or repressed feeling or plan
Our supervisor's speech was a giveaway. Now, I know that he is planning to retire.

[TahlilGaran] English Idioms Dictionary ▲

giveaway
n. (stress on "give")
1. An open secret.
By mid-afternoon, it was a dead giveaway who the new boss would be.
2. A forced or sacrifice sale at which items are sold for much less than their market value.
The Simpson's garage sale was actually a big giveaway.
3. A gift; something one doesn't have to pay for.
The tickets to the concert were a giveaway.

[TahlilGaran] English Idioms Dictionary ▲