Toothless means having no teeth, or having no real power. A toothless grin, a toothless regulator, toothless legislation.
The literal sense belongs to babies and to the very old. The figurative one is much commoner in reporting: a toothless watchdog is one with no power to enforce, and it is among the most-used criticisms of regulators. Note that the compound is Old English and unchanged, and every Germanic language builds it identically.
1adjectiveteethHaving no teeth.
“The baby gave us a big toothless smile.”
2adjectivetoothlessHaving no real power.
“The new law is toothless, because nobody who breaks it can be punished.”
toothless is a state of lacking teeth or power.
Old English tothleas is tooth plus -less. Dutch tandeloos and German zahnlos are built identically, and the word has not changed in a thousand years.
Proto-Germanic
*tanþlausaz — toothless
Old English
tōþlēas
Middle English
tothles
English, today
toothless
From Middle English tothles, from Old English tōþlēas, from Proto-Germanic tanþlausaz (“toothless”), equivalent to tooth + less. Cognate with Dutch tandeloos (“toothless”), German Low German tannlos (“toothless”), German zahnlos (“toothless”), Danish tandløs (“toothless”), Swedish tandlös (“toothless”), Icelandic tannlaus (“toothless”).
Etymology from Wiktionary, CC BY-SA