"Have to step away for a sec," breifly

• "Returning soon," in online shorthand
• "Hang on a sec," in texts
• "Hold on a sec," while texting
• "Returning soon," in texts
• Texter's "Gimme a sec"
• "hold on 1 sec ok?"
• "Putting the phone down for a sec," in textspeak
• "Hang on a sec," to a texter

Wiktionary Word definitions in Wiktionary
init. (alternative case form of BRB nodot=1 English) (gloss: be right back).