Bound morphemes never occur in isolation, that is, are not regularly uttered alone in normal discourse. Such bound forms include prefixes, suffixes, suprafixes, infixes, replacives, subtractives, and some roots.
- Nida (1949), Pag. 81

In special contexts it is always possible to employ a bound form in isolation. For example, in response to the question, 'What is this suffix?' one may reply '-ly'.
- Nida (1949), Pag. 81

Stems, which consist of a root or a root plus some other morpheme, are by definition always bound, e.g. '-ceive' (cf. 'receive') and 'recep-' (cf. 'reception'), 'manli-' (cf. 'manliness') and 'formaliz-' (cf. 'formalizer').
- Nida (1949), Pag. 81

Such bound forms are either (1) nonclitics -additive, replacives, subtractives- or (2) clitics. Nonclitics have a more restricted distribution and occur (for the most part) as immediate constituents with items with which they are phonologically bound. Clitics have a greater freedom of distribution and only accidentally form immediate constituents with the items with which they are phonologically bound.
- Nida (1949), Pag. 103

Forms may be bound in the sense that (1) they never occur alone, e.g. the plural suffix in English, (2) they are bound alternants of free forms, e.g. /wayv-/ (cf. 'wives') in contrast with 'wife' /wayf/, (3) they occur with certain junctures, e.g. 'fresh-' in 'freshman' /fréšmən/, which is bounded by an internal (unmarked) juncture, and (4) they occur with certain suprasegmental features, e.g. '-bird' in 'blackbird' /blǽk-bə̀rd/, which occurs with a secondary stress. The particular type of external juncture is also pertinent.
- Nida (1949), Pag. 105