J

Multiple Entries:
  J    j    joule  

Concise Oxford English Dictionary © 2008 Oxford University Press:
J1 (also j)

▶noun (pl. Js or J's)

• 1 the tenth letter of the alphabet.

• 2 denoting the next after I in a set of items, categories, etc.

• 3 archaic (as a Roman numeral) used instead of an I when in a final position.

Concise Oxford English Dictionary © 2008 Oxford University Press:
J2

▶abbreviation

• 1 jack.

• 2 Japan (international vehicle registration).

• 3 Physics joule(s).

• 4 (in titles) Journal (of).

Concise Oxford English Dictionary © 2008 Oxford University Press:
j/ʤeɪ/

▶symbol (j) (in electrical engineering and electronics) the imaginary quantity equal to the square root of minus one. Compare with i.

Concise Oxford English Dictionary © 2008 Oxford University Press:
joule /dʒuːl/ (abbrev.: J)

▶noun the SI unit of work or energy, equal to the work done by a force of one newton when its point of application moves one metre in the direction of action of the force.

– origin C19: named after the English physicist James P. Joule.