The words and phrases, collectively, that someone understands in speech and writing but does not commonly use.

(immunology) The translocation of active humoral immunity from one individual to another in the form of custom-made antibodies.

(grammar) Synonym of mediopassive

(chemistry) Iron that has been subjected to the action of heat, strong nitric acid, chlorine, etc. It is then not easily acted upon by acids.

(finance) An income that is made using little to no effort, such as pension income, rent, or interest, as opposed to normal employment.

plural of passive aggressor

One who engages in passive-aggression.

(grammar) The form of a transitive verb in which its subject receives the action.

A receive-only radar that uses ambient radio signals for search, tracking, surveillance, identification, guidance and mapping.

(Britain, Canada) Shielding that is chemically inert (unlike reactive armour) and does not require electricity or active sensors to operate. It is usually made of metal, ceramic, or in some cases, composite materials.