in the article it says dissolved in three fold excess HNO3
what does three fold excess mean

oh here is the orginal article

"Place 3.37 mmol of Y2O3, dissolved in three-fold excess concentrated HNO3, diluted with
twice its volume of deionized water, and evaporated to dryness on the hot plate in a
fumehood; fumes of toxic nitrogen dioxide, NO2, will be liberated)."

thx