justification-n; 3 Senses

Sense Number 1: something which serves as a rationale

Commentary: JUSTIFICATION[+relation][+rationale]
NOTE: Does not imply a statement by someone, (Sense 2) but a perceived connection between things
NOTE: often of the form 'X BE justification'

They considered his dictatorship a justification for revolution.
The current rise in inflation may not be a sufficient justification to raise interest rates.

WordNet 3.0 Sense Numbers: 1

Sense Number 2: the act of explaining or defending something

Commentary: JUSTIFICATION[+action][+statement][+explanation][+defense]
NOTE: implies someone's action of explaining something
NOTE: often of the form 'X's justification of Y'

They were not interested in Bob's justification of why he was late for the meeting.
The leader's justification of his actions was not persuasive to the opposition.
The CEO presented his justification for the recent layoffs at the board meeting.

WordNet 3.0 Sense Numbers: 2, 3

Sense Number 3: aligning the words of a text to a margin

Commentary: JUSTIFICATION[+action][+alignment][+margin][+text]

I used left justification for all my paragraphs in that document.
Newspaper columns observe both left and right justification.

WordNet 0.0 Sense Numbers: 3