Synonyms and related words :
Trinkgeld, balance, bonus, boodle, bounty, bribe, bribe money, complimentariness, consideration, costlessness, dividend, donative, double time, expenselessness, extra, fee, free ride, freebie, freeness, gift, gratification, gratuitousness, gravy, grease, honorarium, hush money, incentive pay, inducement, labor of love, lagniappe, largess, leftover, liberality, margin, no charge, overage, overmeasure, overplus, overrun, overset, overstock, oversupply, palm, palm oil, payoff, payola, perks, perquisite, plus, pourboire, premium, protection, remainder, reward, salve, something extra, sop, spare, sportula, surplus, surplusage, sweetener, tip