惜敗 （セキハイ） regrettable defeat, defeat by a narrow margin

惜春 （セキシュン） lamenting the passing of spring, lamenting the passing of one's youth

痛惜 （ツウセキ） deep regret

哀惜 （アイセキ） grief, sorrow

惜しい （おしい） regrettable, disappointing, unfortunate, precious, dear, valuable, too good for, deserving better, almost (but not quite), close (but no cigar)

惜しむ （おしむ） to be frugal, to be sparing, to value, to hold dear, to regret (e.g. a loss), to feel sorry (for), to be unwilling, to be reluctant

惜しむべき （おしむべき） lamentable, regrettable