When an engine is ignited, it produces thrust and boosts the rocket into the sky. After the propellant is used up, delay is activated, producing tracking smoke and allowing the rocket a brief coast.
infirmary (plural infirmaries) 1  A place where sick or injured people are cared for, especially a small hospital; sickhouse. 2  A clinic or dispensary within another institution.
Inflammation that leads to a narrowing of the trachea. Infection of the lungs by the bacterium Mycobacterium tuberculosis. The little swelling, or tubercle, is a colony of bacteria within the soft tissue of the lung that forms a hardened barrier, preventing white blood cells from entering and destroying the bacteria.