(physics) A positively charged nucleus of a helium-4 atom (consisting of two protons and two neutrons), emitted as a consequence of radioactivity; α-particle

(astronomy, physics) A hypothetical class of particle, proposed to explain the dark matter problem.

existing as a part or portion; incomplete / (computer science) describing a property that holds only when an algorithm terminates

(mathematics) A partial derivative: a derivative with respect to one independent variable of a function in multiple variables while holding the other variables constant.

(statistics, transitive) To take the partial regression coefficient.

Composed of separate particles. / (genetics) Pertaining to heritable characteristics which are attributable discretely to either one or another of an offspring's parents, rather than a blend of the two.

(chiefly in the plural) Any solid or liquid in a subdivided state, especially one that exhibits special characteristics which are negligible in the bulk material.

In part, or to some degree, but not completely.

The act of participating, of taking part in something. / The state of being related to a larger whole.

(nautical) The group of sailors who were selected to board an enemy ship and, when in control, to make such repairs to rigging and sail that the ship could be taken to port as a prize