\ban ASCII word boundary
\d+a digit, repeated at least once
\s+any whitespace character, repeated at least once
Non-Capturing Group(?:year|month|day) yearthe literal text year (case sensitive) monththe literal text month (case sensitive) daythe literal text day (case sensitive) s?optionally matches the literal s (11510 / 1638 / 7316) (case sensitive)
\ban ASCII word boundary
Negative Lookahead(?!\s+old\b) \s+any whitespace character, repeated at least once
oldthe literal text old (case sensitive) \ban ASCII word boundary
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