A Lingam (also called Linga or Shiva Linga) is a symbolic representation of the Hindu God Shiva in Shaivism (a tradition in Hinduism) and has a spiritual meaning. It signifies the deity Shiva as the universal generative power, representing all of existence, and all creativity and fertility at the cosmic level. It’s considered a masculine power as opposed to feminine powers, together forming a sacred unity.
Lingam is a Sanskrit word (Sanskrit being the ancient Indian language) literally meaning sign, symbol or mark and it appears in several religious texts originating in ancient India — called the Vedas — notably present in the Upanishads writings from around the 1st millennium BCE.
The word Lingam is also found in Indian Sanskrit texts where it has the meaning of “evidence of God” or “proof of God,” being the visible “expression” of that what is inherently not-visible, without form, yet all-pervasive and omnipresent.
One usually finds Lingam iconography in Hindu temples dedicated to Shiva, or in little Shiva shrines. The Lingam is often depicted standing upright within a disc-shaped platform, the latter being a representation of the Yoni (the feminine counterpart of Lingam, which is a symbol of incarnations of the Shakti Goddess). Apart from the Indian subcontinent, Lingam symbols, images and representations can be found in many other Southeast Asian countries.
Although there are early references of the Lingam being the sexualized procreative phallic representation of the God Shiva, it’s only since the 19th-century that the Lingam has become increasingly associated with the male sex organ (penis) as a result of certain interpretations of Tantric ideas in the Western world. Traditionally however, the Lingam-Yoni concept has been about the masculine and feminine principles in the universe, and not just about sex, sexuality or genitals.
Mind that Tantra and Tantric ideas developed much later in India, around 500 CE, as esoteric traditions of Hinduism and Buddhism emerging from Vishnu, Shiva or Shakti centered practices. In Tantric teachings, emotions, eroticism, sensuality and sexuality obtained more prominence than in previous Indian Vedic systems, and subsequently in the 20th century the Neo-Tantra movement embraced Lingam and Yoni concepts as key elements for its work with (sacred) sexuality.