The meaning of the letters J and K in "JK flip-flop" was previously discussed here, and the meaning of the letter D in "D flip-flop" was previously discussed here.
What does the T stand for in "T flip-flop"?
Electronic – What does the T stand for in “T flip-flop”
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Related Solutions
Here's what wikipedia says: -
According to P. L. Lindley, a JPL engineer, the flip-flop types discussed below (RS, D, T, JK) were first discussed in a 1954 UCLA course on computer design by Montgomery Phister, and then appeared in his book Logical Design of Digital Computers. Lindley was at the time working at Hughes Aircraft under Dr. Eldred Nelson, who had coined the term JK for a flip-flop which changed states when both inputs were on. The other names were coined by Phister. They differ slightly from some of the definitions given below. Lindley explains that he heard the story of the JK flip-flop from Dr. Eldred Nelson, who is responsible for coining the term while working at Hughes Aircraft. Flip-flops in use at Hughes at the time were all of the type that came to be known as J-K. In designing a logical system, Dr. Nelson assigned letters to flip-flop inputs as follows: #1: A & B, #2: C & D, #3: E & F, #4: G & H, #5: J & K. Nelson used the notations "j-input" and "k-input" in a patent application filed in 1953.
Here is a link to a Jack Kilby biography that says he started at TI in 1958 and doesn't mention JK flip flops at all.
This TI website about Jack Kilby also doesn't mention JK flip flops either
If you look halfway down column 13 of this patent filed in 1953 (Granted 1958) you will see mention of inputs to a flip flop called J and K. This patent pre-dates Jack Kilby's time at TI by 5 years: -
A flip-flop can only change state when there is a zero-to-one transition in the incoming clock. If J=1 and K=1, Q output will toggle at half the frequency of the CLK.
It may help you (or confuse you) to know that internally a flip-flop can be formed by cascading two level-sensitive latches, the first of which is low-level latching and the second one is high-level latching. When the same clock is fed to both latch enables, the first latch will settle its state when the clock signal (its latch enable) is low. The second latch will settle its state when the clock signal (its latch enable) is high. Note that the input of the second latch is the output of the first latch. The end result is an edge-sensitive device.
Best Answer
Some people believe that the "T" in "T flip-flop" stands for "toggle," but I believe that it originally was intended to stand for "trigger."
According to the Wikipedia entry on flip-flops,
In Montgomery Phister Jr.'s book Logical Design of Digital Computers (New York: John Wiley & Sons, Inc., 1958, pp. 126-127), he states
Because it seems that Phister was the first one to use the term "T flip-flop" and he used the "T" to stand for "trigger," it seems that this is what it was originally intended to mean.