Four Letter Word

Lunacy Lullaby Loyalty are the words used in a Lexicon.. Perhaps to define a Single 'Four letter word' Familiar with this word Since we're born ! Makes us feel like a free flying bird ! Any Idea about the word i'm talking about? No word No Pen can explain BUT Actions do! Contains true sentiments Emotions without a doubt moreover,It's about US , not ME or YOU ! Hint--Like care shown by Hand when given to eye,Wiping off a tear.. Or by tongue,When screams for another organ ! Or When whole body trembles together in Fear ! Or When Eyes blink together in scorching heat of Sun ! Hands making face neat and clean Lips smiling..showing heart's feelings.. Eyes remaining together though having Nose in between! Ears far apart..yet together they're hearing ! Any guesses?? L-O-V-E is what i'm trying to explain :) Silently to the world it addresses It's like..No Pain No Gain ! Makes your life beautiful and complete Allows to smile..gives strength Tells you heart to Beat ! Keeps all the grieves at arm's length ! The words will End..Ink will Blow ! 'Four letter word' can only be felt ! Poem can go endless as rivers flow ! Protects you as does a car's seat-belt :) :) :) :)