Dalath is the fourth letter of the Syriac abjad, with the numeral value four. It writes d and is one of the six letters with hard and soft readings; soft dalath is the voiced th of English this. It joins only to the right, so the letter after it begins a new connected group.
The feature that defines dalath in practice is the point. Dalath and rish share a single skeleton in every Syriac hand, and the two are told apart only by a dot written below the stroke for dalath and above it for rish. Nothing else separates them. The earliest Syriac writing leaves the point off altogether, and that undifferentiated shape is recorded as a sign in its own right so that editions can reproduce old hands faithfully rather than silently deciding for the reader.
Its name is the inherited Northwest Semitic word for a door, the same noun behind Hebrew daleth and, through the Phoenician sequence, behind the Greek delta.
Dalath is also one of the most frequent letters in Syriac text, because d prefixed to a word is the relative particle and the marker of the genitive: the letter that makes one noun belong to another, and that introduces a clause. A reader meets it at the head of a word constantly, which is exactly the position where the point separating it from rish matters most.