Regular Expressions 101

(?i)applies the following effective flags to the remainder of the pattern: gi

i modifier: insensitive. Matches without distinguishing uppercase and lowercase letters

Non-Capturing Group(?:\b(tree)\b)

\ban ASCII word boundary

Group 1(tree)

treethe literal text tree (case insensitive)

\ban ASCII word boundary

Non-Capturing Group(?:(?!\n)\W)+

+repeats the group contents below at least once:

Negative Lookahead(?!\n)

\na line-feed (newline) character (ASCII 10)

\Wany non-word character

Non-Capturing Group(?:\w+\W+){0,5}?

{0,5}?repeats the group contents below between 0 and 5 times:

\w+any word character, repeated at least once

\W+any non-word character, repeated at least once

\ban ASCII word boundary

Group 2(house)

housethe literal text house (case insensitive)

\ban ASCII word boundary

.*any character (except for line terminators), repeated any number of times

Global pattern flags

g modifier: global. Finds all matches instead of stopping after the first

Detailed match information will be displayed here automatically.

Search reference

Regular Expression

(?i)(?:\b(tree)\b)(?:(?!\n)\W)+(?:\w+\W+){0,5}?\b(house)\b.*

here is a tree with a house
here is a tree 
with a house