Definition of "obscure"

I found myself in an obscure wood.

1892, Denton Jaques Snider, Inferno, 1, 1-2 (originally by Dante Alighieri)

His lamp shall be put out in obscure darkness.

1611, The Holy Bible, […] (King James Version), London: […] Robert Barker, […], Proverbs 20:20

The obscure bird / Clamoured the livelong night.

c. 1606 (date written), William Shakespeare, “The Tragedie of Macbeth”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, [Act II, scene iii]

the obscure corners of the earth

1606, John Davies of Hereford, Bien Venu

The lock was of a kind that Watt could not pick. Watt could pick simple locks, but he could not pick obscure locks.

1953, Samuel Beckett, Watt, Olympia Press

The yawning gap in neuroscientists’ understanding of their topic is in the intermediate scale of the brain’s anatomy. Science has a passable knowledge of how individual nerve cells, known as neurons, work. It also knows which visible lobes and ganglia of the brain do what. But how the neurons are organised in these lobes and ganglia remains obscure.

2013 August 3, “The machine of a new soul”, in The Economist, volume 408, number 8847

They are all couched in a pit hard by Herne's oak, with obscured lights.

c. 1597 (date written), William Shakespeare, “The Merry Wiues of Windsor”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, [Act V, scene iii]

There is scarce any duty which has been so obscured in the writings of learned men as this.

c. 1688', William Wake, Preparation for Death

But Richmond […] appeared to lose himself in his own reflections. Some pickled crab, which he had not touched, had been removed with a damson pie; and his sister saw, peeping around the massive silver epergne that almost obscured him from her view, that he had eaten no more than a spoonful of that either.

1959, Georgette Heyer, chapter 1, in The Unknown Ajax

However, many people—including railwaymen—are only beginning to realise how great is the amount of civil engineering work necessary to achieve adequate clearances for high-voltage overhead equipment under bridges and tunnels; what is involved in the re-signalling needed to permit the increased throughput of traffic (in some places it is unavoidable, to afford better sighting of signals obscured by overhead electrical gear); [...].

1961 December, “Planning the London Midland main-line electrification”, in Trains Illustrated, page 719

I realized that the purpose of writing is to inflate weak ideas, obscure poor reasoning, and inhibit clarity.

1994, Bill Watterson, Homicidal Psycho Jungle Cat, page 62

How! There's bad news. / I must obscure, and hear it.

1623 (first performance), John Fletcher, William Rowley, “The Maid in the Mill”, in Comedies and Tragedies […], London: […] Humphrey Robinson, […], and for Humphrey Moseley […], published 1647, Act IV, scene ii