An offensive or defensive force that uses up all of the population space in a village which is not already being used by buildings. For example, in a fully developed village you can hold 24,000 population and approximately 3,500 will be taken up by buildings (depending on what you build to which levels), leaving you with around 20,500 population spaces. For an offensive village you can fill these with axemen or light cavalry, as well as nukes if you need to take down a wall (keep in mind that choosing only one unit to build will be more powerful when attacking but will take more time to build).
strike at with firepower or bombs; "zap the enemy"
atom-bomb: bomb with atomic weapons
microwave: cook or heat in a microwave oven; "You can microwave the leftovers"
atomic warhead: the warhead of a missile designed to deliver an atom bomb