The katakana syllable ド (do). Its equivalent in hiragana is ど (do).

(sexuality, euphemistic) sadism, sadist / (colloquial) dominant personality

(education) highest academic grading in the S-A-B-C-F scale / (chiefly video games) S, the highest rank or grade (above A) commonly used in ranking systems in video games

small size

(Internet slang) Alternative spelling of さん (san)

manners; etiquette

bow, make the gesture of bending at the waist / return something

(collectible card games, video games) super special rare, or any synonymous variations

SMS

respect, esteem