(slang) Excellent, very good, cool. / Causing death, destruction, or obliteration. / Distressing, uncomfortable.

One who or that which kills. / (figuratively) That which causes stress or is extremely difficult, especially that which may cause failure at a task.

plural of killer

(philately) A cancellation mark that is so heavy that it defaces the postage stamp to which it is applied, devaluing it from a collector's point of view.

(business, US) A retailer that offers a wider selection of merchandise in a category than existing retailers, at lower prices, thereby gaining substantial share of the market and "killing" the existing retailers.

plural of killer cancel

(computing) Any method of inducing physical harm to a computer or peripheral by software means, especially by inserting invalid values into a control register or by building up harmonic oscillations in a hard disk, etc.

A person who contracts to kill a specified person for an agreed sum of money.

(immunology) A natural killer cell

(colloquial) A man unusually attractive to women. / (colloquial) An uncaring womanizer.