General use for something third in a sequence, often in compounds or titles such as albums, seasons, or versions.
He plays third base for the team.
Their third album will be released next month.
third base; third baseman
Baseball term. Depending on context, サード can mean the base, the fielding position, or the player at third base.
The runner advanced to third base.
In high school, he played third base.
third gear
Vehicle or machinery use, especially when talking about gears in a manual transmission.
I shifted down to third before the curve.
I shifted into third gear on the slope.
The shortstop threw the ball to third base.
三塁手 specifically means 'third baseman', whereas サード can refer to either the base, the position, or the player depending on context.
No language of origin is specified. The katakana form is used for English-like 'third' meanings in ordinal, baseball, and gear contexts.