1. to have contact with, to reach out, to communicate with somebody
touch base with someone/about something
This idiom means to contact somebody briefly. The most common reasons for wanting to 'touch base' with someone are to find out how they are doing, what they think about something, or to update them or receive an update about something. ‘Touch base’ can also refer to renewing contact with a person you have not communicated with for a while, like an old friend. This expression can be used in a social context but is more common in a professional one, particularly in the corporate world where it has become increasingly popular. In work, you might 'touch base' with someone to find out what is happening or how something is developing. Phrases with a similar meaning include 'drop a line,' 'check-in with,' and 'reach out to.'