Real Dictionary

second coming after something else
ordinal number: The second item in a series is the one that you count as number two.

second in American English 1
coming next after the first in order of place or time; 2d or 2nd
adjective: next after the first; being the ordinal number for two
noun: a second part

second in American English 2
1⁄60 of a minute of time
noun: the sixtieth part of a minute of time

second in American English 3
to transfer (a military officer) from regular service to special service, civil or military
transitive verb: to transfer (an officer, official, or the like) temporarily to another post

second in British English 1
coming directly after the first in numbering or counting order, position, time, etc; being the ordinal number of two: often written 2nd

second in British English 2
noun: 1⁄60 of a minute of time

second in British English 3
to transfer (an employee) temporarily to another branch, etc

second in Electrical Engineering
noun: A second is a unit of time, and one of the sixty parts that a minute is divided into.

second part of a minute
countable noun: A second is one of the sixty parts that a minute is divided into. People often say 'a second' or 'seconds' when they simply mean a very short time.

second sending someone to do a job
If you are seconded somewhere, you are sent there temporarily by your employer in order to do special duties.