Noun

(uncountable) The process of developing; growth, directed change.

* {{quote-magazine, date=2013-07-19, author= Ian Sample

, volume=189, issue=6, page=34, magazine=(The Guardian Weekly) , title= Irregular bedtimes may affect children's brains , passage=Irregular bedtimes may disrupt healthy brain development in young children, according to a study of intelligence and sleeping habits.  ¶ Going to bed at a different time each night affected girls more than boys, but both fared worse on mental tasks than children who had a set bedtime, researchers found.}}

(uncountable, biology) The process by which a mature multicellular organism or part of an organism is produced by the addition of new cells.

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Of more significance in the nature of branch development ; in the Jubulaceae, as in the Porellaceae, branches are acroscopic and normally replace a ventral leaf lobe.

(countable) Something which has developed.

(real estate, countable) A project consisting of one or more commercial or residential buildings, real estate development.

(real estate, uncountable) The building of a real estate development.

(uncountable) The application of new ideas to practical problems (''cf. research).

(chess, uncountable) The active placement of the pieces, or the process of achieving it.

(music) The second section of a piece of music in sonata form.

Noun

(uncountable) The act of adding anything.

The addition of five more items to the agenda will make the meeting unbearably long.

Anything that is added.

(uncountable) The arithmetic operation of adding.

(music) A dot at the right side of a note as an indication that its sound is to be lengthened one half.

(legal) A title annexed to a person's name to identify him or her more precisely, as in "John Doe, Esq'.", "Robert Dale, '''Mason'''", "Thomas Way, ' of New York ".

(heraldry) Something added to a coat of arms, as a mark of honour; opposed to abatement.