Necessary or necessity may refer to:
Need
An action somebody may feel they must do
An important task or essential thing to do at a particular time or by a particular moment
Necessary and sufficient condition, in logic, something that is a required condition for something else to be the case
Whether man is a necessary or a free agent is a question much discussed.
More Examples
Used in the Middle of Sentence
Many times surgery is necessary to prevent cancer from spreading.
After making the necessary edits always sign out of the system.
Collating was still necessary because they had to insert foldout sheets and index tabs into the documents.
Used in the Ending of Sentence
To alleviate the problem of naming genes, reannotation of genes and proteins using a set of common, controlled vocabulary to describe a gene or protein is necessary.
It is known that wild birds — especially waterfowl and shorebirds — are the main and primary reservoir of AIV in nature which makes epizootological monitoring of populations of these birds necessary.
I am quite sure that too much bed, if not too much sleep, is prejudicial, though a certain amount is absolutely necessary.
Meaning of necessary for the defined word.
Grammatically, this word "necessary" is an adjective. It's also a noun, more specifically, a countable noun.