Apostrophe (noun)

1. A punctuation mark indicating possession or the omission of letters or numbers.
2. A figure of speech in which an address is made to an absent or imaginary person or a personified abstraction.

Origin:

Late 16th century: via latin from greek apostrophos "a turning away", from apo- "away from" + strophos "a turning".

Examples:

1. The apostrophe in "Bob"s house" indicates possession.
2. The apostrophe in "don"t" indicates the contraction of "do not".
3. The apostrophe in "o"clock" is used to indicate the missing letters of the word "of".
4. In the poem, the speaker addresses the night sky in an apostrophe.
5. The politician made an apostrophe to the nation in his speech.