Scriptures: Isaiah 21:4, Isaiah 35:4, Isaiah 41:10, Isaiah 41:13, Heb 2:15, 1 John 4:18, 2nd Timothy 1:7

What is the definition of fear?

noun
an unpleasant emotion caused by the belief that someone or something is dangerous, likely to cause pain, or a threat.

terror, fright, fearfulness, horror, alarm, panic, agitation, trepidation, dread, consternation, dismay, distress; More

verb
be afraid of (someone or something) as likely to be dangerous, painful, or threatening.

Eulabeia originally denoted caution discretion, and later reverence. The meanings fear and reverence are found in 
early Christian lit. It denotes the awesome reverence that all the
earth should have before Yahweh. 
Phobeomai, respect, or to be afraid. It means panic, fright, terror, 
fear, alarm, to be afraid ,respect, awe, or reverence. In the Old 
Testament it can also mean someone or something that is to be 
feared. It may even be applied to God.  The exhortation not to fear 
is also found frequently with regard to what is around us