The French word which is equivalent to the English ‘safety’ is sécurité. When the two letters CQ are spoken they sound similar the first two syllables in sécurité. CQ was first used by the United Kingdom landline telegraphers as a telegraph shorthand to mean “pay attention everyone I have something important to say to all.”
Operators from the United States and some other English speaking countries thought it meant “seek you” and there were some a few who thought CQD meant ‘come quickly distress’ but the European operators knew what it really meant. 1912 CQ meaning “all stations” became internationally accepted.
While CQ is inappropriate to use on a repeater it still can be used in other applications. There is an accepted procedure when calling CQ. Calling CQ on and on 10 to 20 times before giving the appropriate call sign is not that accepted procedure.
Normally it is advised to call CQ three times followed by giving your call sign three times and then repeat this two more times. The opening line of this post illustrates this when using voice communications. By following this procedure it gives the opportunity for stations tuning the band looking for a QSO to find you, set their equipment on your frequency in preparation to answer. Long drawn out CQ calls will sometimes result in stations leaving and looking for someone else who is not quite as long winded.
The three CQ followed by three times giving the call sign all being repeated two more times is not a set in stone practice but in most instances is recommended. Sometimes it might be best to abbreviate this by not repeating the whole thing three times.