The expression "pat-back" refers to the act of congratulating someone or giving them recognition for their achievements. Some synonyms for this term include "applaud," "praise," "compliment," "commend," "hail," and "laud." These words all convey a positive sentiment towards the person being recognized and can be used interchangeably with "pat-back" depending on the context. Other similar phrases include "give someone a round of applause," "tip one's hat," "raise a glass to," and "acknowledge someone's efforts." Using these synonyms can help diversify your vocabulary and avoid repetition when expressing admiration or gratitude towards others.