Corpus Juris Secundum, Volume XI, at page 515 ascribes the following meanings to the word bonus: " An allowance in addition to what is usual current or stipulated ; a sum given or paid beyond what is legally required to be paid to the recipient; something given in addition to what is ordinarily received by or strictly due to the recipient" and adds: It has been said to carry the idea of something uncertain and indefinite, something which may or may not be paid depending on varying circumstances and under particular conditions has been said to imply a benefit accruing to him who offers it and an inducement to the offeree