guerrilla

noun

1. A soldier in a small independent group, fighting against the government or regular forces by surprise raids.

   “The right-wing paramilitary's offensive against the Marxist guerrillas failed because they did not know the terrain well enough.”

   “From the start of its operations in Colombia, the company was on guard against the decadeslong civil strife in the country between left-wing guerrilla and right-wing paramilitary groups, witnesses have testified.”

   “After a harsh police crackdown last week fueled anger and swelled protests, President Dilma Rousseff, a former guerrilla who was imprisoned under the dictatorship and has now become the target of pointed criticism herself, tried to appease dissenters by embracing their cause on Tuesday.”

2. (archaic)A non-official war carried out by small independent groups; a guerrilla war.
3. A marketer who uses guerrilla marketing techniques.
4. A maker of guerrilla television.

adj

1. Relating to, using, or typical of guerrilla warfare, or its principles of small independent or non-official perpetrators.

   “Wherever Nicholson was most wanted, there he was sure to be found. What his life was at this time may be seen from a letter he wrote to his mother: 'I am leading a very guerrilla sort of life with seven hundred horse and foot raised among the people of the country. The chieftain who is in rebellion has eight regular regiments and sixteen guns, so that I am unable to meet them openly in the field.'”

   “On the other hand, after the fall of Feng Ling Tu, the operations of Central Shansi, and Suiyuan, troops were more guerrilla than orthodox in nature.”

   “The Slovak uprising in the latter days was not guerrilla in character, which, incidentally, may have been one of the reasons for its failure.”

2. Relating to, using, or typical of guerrilla marketing.

   “We took a very guerrilla approach to marketing Goin' Hollywood, in keeping with the irreverent tone of the game.”

   “"Mozilla's marketing has been very guerrilla. You're not seeing it spend millions of dollars on TV. Instead, it's a powerful ground swell.”

   “My style is more guerrilla. I grew up in a village, a very suppressed environment. I was like one of those young kids who hated the whole conventional way of doing things. So when I started to make films it was very hand-made, very fast.”

3. Using unconventional, non-traditional, non-mainstream and often subversive practices to achieve something.

   “guerrilla marketing”

   “guerrilla tourism”

   “guerrilla gardening”

   “The Boston demonstration, which will feature singing and guerrilla theatre, will begin at 12 noon in front of the Park Street Subway station.”

   “Jackass’s guerrilla, nonnarrative format”