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ad. In an irregular or informal manner; without the usual forms.

ad. In an informal manner.

In an informal manner; irregularly; without the usual forms; unceremoniously.

ad. without formality

ad. with the use of colloquial expressions

"After the meeting, I met privately with Secretary of State Al Haig and told him to call our ambassador in Tokyo, Mike Mansfield, and have him pass the word informally to Japanese Foreign Minister Masa-yoshi Ito, who was scheduled to make a visit to Washington in a few days, that pressure was building in Congress for passage of a bill establishing mandatory quotas."

address (someone) informally   

inform   

abnormally    formally    normally