缇 is best known from the story of 缇萦, a girl in the Han dynasty who petitioned Emperor Wen to abolish cruel corporal punishments in order to save her father. Her act of filial piety became legendary.
纟 is the silk radical 糸 in left-side form. It marks 缇 as a textile word - specifically a kind of orange-red silk fabric - and groups it with 红 (red), 绛 (crimson), and 绸 (silk).
是 supplies the reading, drifting from shì to tí along an old onset alternation. The same phonetic surfaces in 提 (lift), 题 (topic), and 堤 (embankment), all hovering around the t- and sh- syllables of the di/shi family.
