Noun

(en noun)

A Hindu or Sikh spiritual teacher.

* 1817 , William Ward, History, Literature and Religion of the Hindoos , vol II:

When the gooroo arrives at the house of a disciple, the whole family prostrate themselves at his feet, and the spiritual guide puts his right foot on the heads of the prostrate family.

* 2010 , Wendy Shanker, The Guardian , 10 May 2010:

Traditionally, a guru is a spiritual teacher who guides a student on the road to Enlightenment, or finding God.

(sometimes, humorous) An influential advisor or mentor.

* 2004 , ‘Vintage technology’, Time , 18 Oct 2004:

Many oenophiles rely on the ratings and recommendations of wine guru Robert Parker when selecting the perfect bottle.

Noun

(en noun)

One who goes before, as into the wilderness, preparing the way for others to follow.

A person or other entity who is first or among the earliest in any field of inquiry, enterprise, or progress.

* {{quote-magazine, date=2013-05-10

, author=Audrey Garric , title=Urban canopies let nature bloom , volume=188, issue=22, page=30 , magazine=(The Guardian Weekly) citation , passage=As towns continue to grow, replanting vegetation has become a form of urban utopia and green roofs are spreading fast. Last year 1m square metres of plant-covered roofing was built in France, as much as in the US, and 10 times more than in Germany, the pioneer in this field.}}

Some people will consider their national heroes to be pioneers of civilization.

Certain politicians can be considered as pioneers of reform.

(obsolete, military)   A soldier detailed or employed to form roads, dig trenches, and make bridges, as an army advances; a sapper.

A member of any of several European organizations advocating abstinence from alcohol.

(Communism)   A child of 10–16 years in the former Soviet Union, in the second of the three stages in becoming a member of the Communist Party.