Lakkha?a means mark or seal. An imperial seal certifies the authenticity of documents, allowing for passage without hindrance. Here, it is used in analogy for the principal doctrines of Buddhism. If any doctrine is in line with the "Seals of Dhamma", it can be regarded as authentic teaching of the Buddha. (If it has been mastered, all Dhammas will be grasped without obstruction.) That is why they are called the "Seals of Dhamma". If, after "All phenomena are impermanent, all dhammas are devoid of self", we add "Nibbāna is serene", we have what are called the Three Seals of the Dhamma. With the addition of "All defiled (sāsava) dhammas lead to suffering", we have the Four Seals of Dhamma.
印就是印璽。國王的印璽可以證明文件的真實(有通行無阻的作用)。借以比喻佛教的主要教義,也以符合“法印”而證明其為真正佛法(掌握了它,便能對一切法通達無礙),所以稱為法印?!爸T行無常,諸法無我,涅槃寂靜”,并稱三法印,或者加上“有漏皆苦”,亦稱四法印。