When tennis was invented in 1874, it was called "sphairistike"

Sphairistike is the name of an ancient Greek game that a Welsh inventor Major Walter Wingfield (1833 – 1912) borrowed for the game he patented on February 23, 1874, in part a conflation of elements borrowed from three different games: the net from badminton, the ball from fives, and the scoring from racquets. If that name had caught on, we would now be watching the Wimbledon Sphairistike Championships.

Luckily ,it didn’t, for the very good reason that only those few people well versed in ancient Greek knew how to say it. Most converted it into a three-syllable word that roughly rhymed with “pike”. This was soon abbreviated either to sticky or the mock-French stické.
In his patent, Walter Wingfield also called it lawn tennis, chosen to distinguish it from the much older indoor game called court tennis.

The word tennis is said to have been derived from the French word, tenez ,the imperative form of the verb tenir, (to hold).The server announced "Tenez!" (meaning "I am about to serve!"),and then served the ball.

Racquet comes from the Arabic rakhat, meaning the palm of the hand.

Deuce comes from à deux le jeu, meaning "to both is the game" (that is, the two players have equal scores

The convention of numbering scores "15", "30" and "40" comes from quinze, trente and quarante, which to French ears makes a euphonious sequence, or from the quarters of a clock (15, 30, 45) - with 45 simplified to 40.

Tennis can be traced as far back as the ancient Greek game of sphairistike (Greek: Σφαιριστική), and is mentioned in literature as far back as the middle ages. Sir Gawain, a knight of King Arthur's round table, plays tennis with a group of giants in The Turke and Gowin.
Also in the late 16th century, when William Shakespeare mentions "tennis balles" in his play Henry V, when a basket of them is given to King Henry as a mockery of his youth and playfulness.

At the suggestion of future British prime minister Arthur Balfour, Walter Wingfield eventually decided on "lawn tennis," a name that he had also patented for the game.

A modified version of his game became hugely popular under that name,but it was soon abbreviated just to tennis, so that the aficionados of the older game in snobbish retaliation started to call theirs real tennis, a term later mistakenly converted to royal tennis in Britain and some other countries.

When Wingfield patented it in 1874. With the patent came an eight-page rule book, titled “Sphairistike or Lawn Tennis” with the subheading “The Major’s Game of Lawn Tennis".

In the late 19th century, tennis spread first throughout the English-speaking world, particularly among the upper classes. Tennis is now played at all levels of society, by all ages, and in many countries around the world. Except for the adoption of the tie-breaker in the 1970s, its rules have remained remarkably unchanged since the 1890s.

Walter Wingfield also invented the butterfly bicycle.He was inducted into the International Tennis Hall of Fame in 1997.