an associative relation
"The study revealed no significant linkage between childhood trauma and adult success in their survey data."
(genetics) traits that tend to be inherited together as a consequence of an association between their genes; all of the genes of a given chromosome are linked (where one goes they all go)
"Because of linkage, these two eye-color genes were always passed down to the offspring together."
a mechanical system of rods or springs or pivots that transmits power or motion
"The car's suspension relies on a complex linkage to absorb bumps and transmit smooth motion to the chassis."
the act of linking things together
"The engineer focused on the structural linkage that holds the bridge's main beams together."
A mechanical device that connects things.
"The engineer adjusted the linkage to ensure the gear shifted smoothly without binding."
In plain English: Linkage is when two things are connected so that they move together.
"The new software update improved the linkage between the printer and the computer, so files print automatically now."
Usage: Linkage refers specifically to a system of connected parts, such as rods or chains, used in machinery to transmit motion from one point to another. Do not use this term when describing an abstract connection between ideas or events; for those contexts, choose words like "connection" or "relationship."
The word linkage comes from combining the verb link with the suffix -age to indicate an action or result. It entered English as a straightforward formation meaning the act of linking things together.