(chiefly US) An at-grade crossing between a railroad line and an ordinary road, with tracks and road at the same level.

(US, education) The first year of grade school, the period in school that comes after kindergarten and before second grade. Children usually begin first grade at age six.

(often attributive) A standard of purity suitable for medicinal use.

(idiomatic) To prove satisfactory; to be successful or worthy of merit.

(US, rarely Canada, education) An elementary school or primary school

Of inferior quality.

(of a radioactive or other substance) Of a purity suitable for the manufacture of weapons. / (by extension, informal) Extreme.

plural of grade crossing

(US, education) The period in school that comes after tenth grade and before twelfth grade.

(US, education) The period in school that comes after second grade and before fourth grade.