reliable

from The American Heritage® Dictionary of the English Language, 5th Edition.

• adjective Capable of being relied on; dependable.
• adjective Yielding the same or compatible results in different clinical experiments or statistical trials.

from The Century Dictionary.

• That may be relied on; fit or worthy to be relied on; worthy of reliance; to be depended on; trustworthy.
• Synonyms Trustworthy, trusty.

from the GNU version of the Collaborative International Dictionary of English.

• adjective Suitable or fit to be relied on; worthy of dependance or reliance; trustworthy.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adjective Suitable or fit to be relied on; worthy of dependence or reliance; trustworthy
• adjective signal processing Such that either a sent packet will reach its destination, even if it requires retransmission, or the sender will be told that it didn't
• noun Something or someone reliable

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• adjective conforming to fact and therefore worthy of belief
• adjective worthy of reliance or trust
• adjective worthy of being depended on