What Is APL? APL stands for Arm Pit Length. This makes reference to hair that extends down to the arm pit. POSTS RELATED TO THIS TERM How To Get 4b Hair To Waist Length In 3 Years Terminal Length – How Long Can Your Hair Actually Grow? The Staggered Protective Styling Regimen – Grow Your Hair Long … Related Posts:What is BSL?What is CBL?What is MBL?What is the LOC or LCO method?What Does DC Or DT Mean?What Does HH Mean?What is A TNC?What is S&D? TweetPinShare0 Shares Black Hair Information > Glossary > What Is APL?