onto

Multiple Entries:
  onto    on  

Concise Oxford English Dictionary © 2008 Oxford University Press:
onto/ˈɒntə/

▶preposition variant form of on to (see on).

usage: The preposition onto written as one word (instead of on to) is widely used, but is still not wholly accepted as part of standard British English (unlike into, for example). However, in US English, onto is standard.

Concise Oxford English Dictionary © 2008 Oxford University Press:
on/ɒn/

▶preposition

• 1 physically in contact with and supported by (a surface).

  ■ located somewhere in the general surface area of (a place).

  ■ on to.

  ■ in the possession of.

• 2 forming a distinctive or marked part of the surface of.

• 3 about; concerning.

  ■ having (something) as a basis.

• 4 as a member of (a committee, jury, etc.).

• 5 having (something) as a target, aim, or focus.

• 6 having (something) as a medium for transmitting or storing information.

  ■ being broadcast by (a radio or television channel).

• 7 in the course of (a journey).

  ■ while travelling in (a public service vehicle).

• 8 indicating the day or part of a day during which an event takes place.

  ■ at the time of.

• 9 engaged in.

• 10 regularly taking (a drug or medicine).

• 11 paid for by.

• 12 added to.

▶adverb

• 1 physically in contact with and supported by a surface.

  ■ (of clothing) being worn by a person.

• 2 indicating continuation of a movement or action.

  ■ further forward; in an advanced state.

• 3 (of an event) taking place or being presented.

  ■ due to take place as planned.

• 4 (of an electrical appliance or power supply) functioning.

• 5 (of an actor) on stage.

  ■ (of an employee) on duty.

▶noun (also on side) Cricket the leg side.

– phrases
be on about Brit. informal talk about tediously and at length.
be on at Brit. informal nag or grumble at.
be on to informal

• 1 be close to uncovering an illegal or undesirable activity engaged in by (someone).

• 2 (be on to something) have an idea that is likely to lead to an important discovery.

on and on continually; at tedious length.
on to moving to a location on the surface of (something) or aboard (a bus, train, etc.).

– origin OE on, an, of Gmc origin.