From QRZ.Com, the Icom handout, and Part 97 Of The FCC Rules -
Ham Radio Glossary - An overview of amateur radio terms.

Yagi
An antenna consisting of two or more elements ("arms" that run
perpendicular to a common boom) which are fed parasitically from one
or more "driven" elements. The number of elements is proportionate to
the gain (more elements means more gain).

YL
"Young Lady"; short for "girlfriend"
--- SBBSecho 3.20-Win32
* Origin: The Thunderbolt BBS - Little Rock, Arkansas (1:2320/33)