noun

modesty or shyness resulting from a lack of self-confidence.

I say this with some diffidence

shyness,bashfulness,unassertiveness,modesty,modestness,self-effacement,humility,humbleness,meekness,timidity,timidness,timorousness,reserve,reticence,introversion,insecurity,self-doubt,apprehension,uncertainty,hesitancy,nervousness,reluctance,restraint,inhibition,unease,uneasiness,self-consciousness,shame,embarrassment,sheepishness