(uncommon) Initialism of Sara Delano Roosevelt.

Initialism of synchronous digital hierarchy. / Initialism of subtitles for the deaf and hard of hearing.

(Christianity) Initialism of Seventh-day Adventism, a Protestant denomination. / (Christianity) Initialism of Seventh-day Adventist. / Initialism of specially denatured alcohol.

(video games) Initialism of Speed Demos Archive.

(military) Initialism of (Japanese) Self-Defence Force(s). / (military) Initialism of Syrian Democratic Forces.

(astronomy) Initialism of scattered-disc object. / (military) Initialism of squadron duty officer.

(space science, US) Initialism of Solar Dynamics Observatory.

plural of SDA

Initialism of Spatial Division Multiple Access.

Initialism of San Diego Museum of Art.