Good Knot Serves a useful purpose, is easy to tie, doesn't come undone on it's own, and is easy to untie.
Bend A knot is a bend when you join two ropes together.
Hitch A knot is a hitch when you make a rope fast to another object.
Working End Part of the rope being manipulated.
Standing Part Inactive section of the rope.
Bight Any curved section, slack part, or loop between the two ends of a rope.
Overhand Loop working part goes over the standing part.
Underhand Loop working part goes under the standing part.
Turn One round of rope.
Yarn Fibers twisted together (typically Z lay).
Strand Two or more large yarns twisted together (typically S lay).
Rope Several strands twisted together (typically Z lay).
Cable Several Ropes twisted together (typically S lay.).
S lay The twist matches the middle of an S.
Z lay The twist matches the middle of a Z.

Each knot used for BSA rank advancement is marked with one or more of the following codes:

2w 2nd grade Wolf
1st First Class
B Bear
4w 4th grade Webelos
tF Tenderfoot