What do the three-letter words below have in common, and what are the two five-letter words, either of which describes how they got to share that common feature?

ALE
ARE
OUR
RAP
RUB

HINT:
Definitions of the five-letter words:
1. Speak derisively
2. Provide recon

Answers:

What the clue word have in common:

Each word becomes a new one when preceded by SC:
SCALE, SCARE, SCOUR, SCRAP, SCRUB

The two five-letter words that explain the commonality:

1. SCOFF    (SC off)
2. SCOUT   (SC out)

Credit: Dan Naddor