Crossword clues for the word: NECESSITY The word NECESSITY has appeared as an answer to at least 8 crossword clues on different crossword puzzles. Crossword clues for NECESSITY Showing 1 to 8 of 8 results Clue(s) Indispensable thing Invention s mother It's indispensable Need Penna. fort of 1754 attack Requirement Something essential or indispensable The mother of invention, it's said