Regular Expressions 101

/?optionally matches the literal / (47₁₀ / 57₈ / 2F₁₆)

\h*any horizontal whitespace character, repeated any number of times

Group 1(\w+)

\w+any word character, repeated at least once

Positive Lookahead(?=(?:\h*/\h*\w+)+metastase\b)

Non-Capturing Group(?:\h*/\h*\w+)+

+repeats the group contents below at least once:

\h*any horizontal whitespace character, repeated any number of times

/the literal / (47₁₀ / 57₈ / 2F₁₆)

\h*any horizontal whitespace character, repeated any number of times

\w+any word character, repeated at least once

metastasethe literal text metastase (case sensitive)

\ban ASCII word boundary

Non-Capturing Group(?:\h*/)?

?repeats the group contents below at most once:

\h*any horizontal whitespace character, repeated any number of times

/the literal / (47₁₀ / 57₈ / 2F₁₆)

Global pattern flags

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

m modifier: multiline. Causes ^ and $ to match the start and end of each line, not only the start and end of the string

Detailed match information will be displayed here automatically.

Search reference

Regular Expression

/?\h*(\w+)(?=(?:\h*/\h*\w+)+metastase\b)(?:\h*/)?

New

lever/botmetastase
kidney/lever/botmetastase
pancreas/kidney/lever/botmetastase

lever / botmetastase
kidney /lever/  botmetastase
pancreas /kidney  /      lever/ botmetastase

Substitution

$1metastase