What is "sutram"

The dictionary gives the meaning of the Sanskrit or Tamil expression, Sutram or Sutra , as string or thread, formula, short sentence or aphoristic rule, girdle, stroke, yarn or plan. Unique to Sanskrit literature, Tamil literature and Pali literature of Hinduism, Jainism and Buddhism, they are short cryptic sentences, methodically written as memory-aids, stringing step by step a particular topic or text in its entirety. There are hundreds of Sanskrit texts found written in the Sutra-format such as Kapila Sutram, Samkhya-pravachana Sutram, Brahma Sutra, Jaimini Sutram, Tatvartha Sutram, Kalpa Sutra, etc.