Answer:

PSST

Answer	Crossword Clue
PSST	"Hey, you!"
PSST	Attention-getter
PSST	"Hey you, c'mere!"

PSST	"Hey, over here!"
PSST	Attention getter
PSST	Sibilant attention getter
PSST	Subtle "Over here!"
PSST	Verbal nudge
PSST	Sibilant summons
PSST	Attention-getting sound
PSST	Furtive "Hey!"

PSST	Sibilant "hey"
PSST	Conspiratorial "Hey!"
PSST	Furtive whisper
PSST	Head-turner
PSST	Sibilant "Hey!"
PSST	"Over here!"
PSST	Sibilant "Ahem!"
PSST	Hey, over here!

PSST	"Wanna hear a secret?"
PSST	"Hey, listen up!"
PSST	Sound from a note passer
PSST	"Hey you!"
PSST	"You there!"
PSST	"Hey there!"
PSST	"Yo!" quietly
PSST	Call for attention

PSST	Hissed "Hey!"
PSST	Sibilant "Hey, you!"
PSST	"Hey!," in a library
PSST	Hissed "Hey you!"
PSST	Hushed "Hey!"
PSST	Muffled "Yo!"
PSST	Sibilant attention-getter
PSST	Subtle alert

PSST	Hushed "Hey you!"
PSST	Sibilant "Over here!"
PSST	"Hey!" in class
PSST	Hey, the quiet way
PSST	Note passer's signal

Crossword

a puzzle consisting of a grid of squares and blanks into which words crossing vertically and horizontally are written according to clues.