n [U]
(a) determining or regulating the time when an action or event occurs 定时; 调整时间
*[attrib 作定语] a `timing device 定时装置
* The timing of the announcement was rather unexpected. 选择那个时间公布, 真出人意料.
* valve timing, ie the time at which valves in a motor engine open and close 阀定时.
(b) skill in this, as a way of achieving the desired result 时间的选择; 时机的掌握
*He's not playing his shots well his timing is faulty. 他没打好--时间掌握不当.
* A good actor must learn the art of timing, ie when to deliver a line most effectively. 要想当个好演员就要学会掌握道白的时间分寸.

n
[U]
the skill of doing something at exactly the right time
perfect/good/bad etc timing
　He was just walking into the restaurant when we got there. Perfect timing.
　He told jokes with an exquisite sense of timing .
[U and C]
the time when someone does something or when something happens, especially when you are considering how suitable this is
timing of
　The President and I did not discuss the timing of my departure.
　Ferry schedules and precise timings are subject to weather conditions on the day of departure.
[U]
the way in which electricity is sent to the spark plugs in a car engine