Abbreviation of road. / Abbreviation of rad (“unit of measure”). / (knitting, firearms) Abbreviation of round.

(law) Abbreviation of road.

Marks ordinals written in digits when the final term of the spelled number is "third"

(medicine) Initialism of respiratory distress syndrome. / Initialism of radio data system. / (chemistry) Initialism of rate-determining step. / Initialism of relational database service.

plural of rd

(exclusively as part of street names) Abbreviation of road.

(astronomy) Initialism of red dwarf. / (US) Initialism of restricted data. / (US, uncountable) Initialism of rural delivery, formerly used when addressing mail.

plural of RD

Marks ordinals written in digits when the final term of the spelled number is "thirds"

Initialism of research, development and demonstration.