Seven letter words change one or two letter to make a new word

blocker

blacken

lacking

Gill-man
(Do we need a ruling on hyphens? I feel like I’m cheating. But how often do you get to use Gill-man?)

Someone asked about, and posted, a hyphenated word sometime back and no one objected.

margins

I’m pro-hyphens, but I can usually think of a word that doesn’t require them.

amongst

monster

sternum

numbers

slumber

clamber

climber

plumber

grumbly

burgler

regular

jugular

jaguars

sausage

guessed