📒 the fourth letter of the Greek alphabet (Δ, δ)
📒 an area of land, like a triangle in shape, where a river has split into several smaller rivers before entering the sea
📒 a variant (= form) of the SARS-CoV-2 virus that was first reported in late 2020 and named ‘Delta’ in 2021. It became the main form of the virus worldwide until the Omicron variant appeared in late 2021.